Common Virus 
Symptoms

Things to look for when you think you have a virus?

Courtesy of NAI AVERT Labs

1. Anti-virus software picks up virus fragments, but no noticeable system or file changes occur
2. This is a memory infection. 
3. Unaccountable system activities 
4. Lost, renamed, or altered files
5. Altered file templates
6. Nonsensical system messages
7. New text strings in the boot sector (i.e. "Your PC is now Stoned!")
8. Absence of text strings in the boot sector
9. Code size the MBR of your hard drive dramatically increases
10. Changes in file sizes on hard drives versus recent back-ups
11. Files with multiple file extensions (i.e. abc.HTML.pif)
12. Word: inability to convert an infected Word document to another format. 
13. Word: infected files have the Template format, because when infecting, Word viruses convert files from the Word Document format to Template format.
14. Word 6 only: inability to save a document to another directory or disk with the "Save As" command. 
15. Excel/Word: "alien" files are present in the STARTUP directory 
16. Excel versions 5 and 7: Cookbooks contain redundant and hidden Sheets. 
17. Changes in Microsoft office system configuration files, visible as changes to the tool bars and menus