Issue
When accessing Citrix-delivered applications via the Citrix Web Interface, you can log in and see the icons for applications. You have the Citrix client for PC installed but when you try to start one of them, the message ICA file not found is displayed and the application does not start.
 

Cause
This behavior is caused by the temporary Internet files cache becoming too large. When the ICA file that is used to launch applications from the Web Interface is downloaded, the delay is too long because the operating system can't find the file among the temporary Internet files fast enough and the above error is displayed.

Solution
Open Internet Explorer, click Tools>Internet Options>on the General Tab, click the Delete Files button.  Restart the browser and you should be able to connect to Citrix applications.
 

Cause # 2
Users may also receive the following error message when launching published applications through NFuse: ICA File Not Found.

The following scenarios are known to produce this error message - The Web pages were presented with the HTTPS protocol and the client cannot save encrypted pages to disk. When a user clicks an application icon, the Launch.ica file is downloaded from the Web server and then executed by the local client. If the NFuse Web server is using SSL (https://...) and your browser is configured so it does not save encrypted pages to disk, the Launch.ica file cannot be written to disk and the client has no file to open.

To resolve this issue:
On the client device, in Internet Explorer, go to Tools>Internet Options.Select the Advanced tab. Beneath the Security section of options, clear the option called Do Not save encrypted pages to disk.

Additional Information
When users access the Internet, certain applications (for example, Gator, download accelerators, and so on) are installed on the users’ systems without acknowledgement. The problem occurs on Windows clients Windows 9x, XP, or Me.