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                                                                  EXHIBIT (a)(3)

                          Notice of Guaranteed Delivery

                                       for

                        Tender of Shares of Common Stock

                                       of

                         CSI Computer Specialists, Inc.

                                       by

                            Interactive Systems, Inc.

                    (NOT TO BE USED FOR SIGNATURE GUARANTEES)

     This  Notice  of  Guaranteed  Delivery  (or one  substantially  in the form
hereof) must be used to accept the Offer (as defined herein) if (a) certificates
representing  shares of Common  Stock,  par value  $0.001 per share (the "Common
Shares"),  of CSI Computer  Specialists,  Inc., a Delaware  corporation  ("Share
Certificates"),  are not  immediately  available;  (b) time will not  permit all
required  documents to reach  Continental  Stock  Transfer & Trust  Company (the
"Depositary"),  on or prior to the  Expiration  Date (as defined in the Offer to
Purchase) of the Offer;  or (c) the procedure for  book-entry  transfer,  as set
forth in the Offer to  Purchase,  cannot be completed  on a timely  basis.  This
Notice of Guaranteed Delivery may be delivered by hand or mail or transmitted by
facsimile  transmission  to the  Depositary.  See  Section  3,  "Procedures  for
Accepting the Offer and Tendering Shares," of the Offer to Purchase.

                         The Depositary for the Offer is

                   CONTINENTAL STOCK TRANSFER & TRUST COMPANY

By Mail:                    By Hand:                    By Overnight Courier:

Reorganization Department  Reorganization Department   Reorganization Department
2 Broadway, 19th Floor     2 Broadway, 19th Floor      2 Broadway, 19th Floor
New York, NY 10004         New York, NY 10004          New York, NY 10004

                         Facsimile Transmission Number:
                                 (212) 509-5150

                   Confirm Receipt of Facsimile by Telephone:
                                 (212) 845-3226

     DELIVERY OF THIS NOTICE OF GUARANTEED  DELIVERY TO AN ADDRESS OTHER THAN AS
SET FORTH ABOVE, OR TRANSMISSION OF INSTRUCTIONS VIA FACSIMILE TO A NUMBER OTHER
THAN AS LISTED ABOVE DOES NOT CONSTITUTE A VALID DELIVERY.

     THIS  NOTICE  OF  GUARANTEED  DELIVERY  IS  NOT  TO BE  USED  TO  GUARANTEE
SIGNATURES.  IF A  SIGNATURE  ON A  LETTER  OF  TRANSMITTAL  IS  REQUIRED  TO BE
GUARANTEED BY AN "ELIGIBLE  INSTITUTION"  UNDER THE INSTRUCTIONS  THERETO,  SUCH
SIGNATURE  GUARANTEE  MUST  APPEAR  IN  THE  APPLICABLE  SPACE  PROVIDED  IN THE
SIGNATURE BOX IN THE LETTER OF TRANSMITTAL.





Ladies and Gentlemen:

     The  undersigned  hereby tenders to Interactive  Systems,  Inc., a Virginia
corporation, upon the terms and subject to the conditions set forth in the Offer
to  Purchase,  dated April 26, 2000 (the "Offer to  Purchase"),  and the related
letter of  transmittal  (the "Letter of  Transmittal,"  which  together with the
Offer to Purchase,  as amended or supplemented  from time to time,  collectively
constitute the "Offer"),  receipt of each of which is hereby  acknowledged,  the
number of Common Shares  indicated  below  pursuant to the  guaranteed  delivery
procedures  set forth in  Section 3,  "Procedures  for  Accepting  the Offer and
Tendering Shares," of the Offer to Purchase:

Signature(s)

Name(s)

                             (Please Type or Print)

Address
Zip Code

Area Code and Tel. No(s).

Number of Common Shares

Certificate Nos. (If Available)

               (Check  box if  Common  Shares  will be  tendered  by  book-entry
               transfer) The Depository Trust Company

Dated

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                                    GUARANTEE

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                    (NOT TO BE USED FOR SIGNATURE GUARANTEE)

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     The undersigned,  a bank, broker, dealer, credit union, savings association
or other  entity that is a member in good  standing of the  Securities  Transfer
Agents Medallion Program (an "Eligible Institution"), hereby guarantees delivery
to the  Depositary,  at its  address  set  forth  above,  of Share  Certificates
tendered  hereby in proper form for transfer,  or confirmation of the book-entry
transfer of Common Shares into the Depositary's  account at The Depository Trust
Company,  in either case together with delivery of a properly completed and duly
executed  Letter  of  Transmittal  (or  facsimile  thereof)  with  any  required
signature  guarantee,  or an  Agent's  Message  (as  defined  in  the  Offer  to
Purchase), and any other documents required by the Letter of Transmittal, within
three  trading  days after the date of  execution  of this Notice of  Guaranteed
Delivery.

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     The Eligible  Institution  that  completes this form must  communicate  the
guarantee to the Depositary and must deliver the Letter of Transmittal and Share
Certificates to the Depositary within the time period indicated herein.  Failure
to do so may result in financial loss to such Eligible Institution.

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Name of Firm

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Authorized Signature

Name

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                             (Please Type or Print)

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- --------------------------------------------------------------------------
Title

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Address
Zip Code

Area Code and Tel. No.

Dated

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               NOTE:  DO NOT SEND SHARE  CERTIFICATES  WITH THIS  NOTICE.  SHARE
               CERTIFICATES SHOULD BE SENT WITH YOUR LETTER OF TRANSMITTAL.