Hopper virus infects .VBS files and Word documents, as well as HTML files. VBS/Hopper.A infects other .VBS files by prepending it's code to the original file.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
More information on scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more information.
Some variants of this virus family also infect HTA and HTT files. Some of them lower the security settings of IE's zones. To ensure that the virus works on all platforms, when infecting VBS and DOC files, it comments out the HTML-specific part of itself. It infects documents when closes them.
Some variants of VBS/Hopper are able to infect Excel files as well.
Technical Details:Katrin Tocheva, F-Secure