Here are some of the tell-tale signs that your computer may exhibit if it's infected by a virus:
- Changes in the size of programs
- Changes in the file last modified date or timestamp
- Longer program load times
- Slower system operation
- Reduced memory or disk space
- Bad sectors on your hard drive or SSD
- Unusual error messages
- Unusual screen activity
- Failed program execution
- Failed system bootups when booting — or accidentally booting — from the A: drive.
- Unexpected writes to a drive
Other ways to tell if your computer has a virus
These symptoms don't guarantee that a virus is present; there are many other possibilities that can cause them. If you're still not sure whether you've got a virus or not, try these steps next:
1. Get the most recent version of a quality antivirus program on a computer that's behaving normally; install it on a clean floppy and write-protect the diskette. Boot the suspect computer with a clean bootable diskette and run the antivirus program from the newly created disk.
If the program gives you the option to use heuristics, enable them only after the initial scan finds nothing and then scan again. (But don't turn on heuristics during the first scan, because they'll increase the probability of false alarms.)
2. If nothing shows up, consider contacting the support center of the antivirus program for further direction.
What should I do if I find a virus on my computer?
Found a virus? Most of the experts we consulted said not to rely on the antivirus to clean the infected file. Instead, replace it with the original clean version.
Some of the material in this article comes from Wolfgang Stiller, the developer of Integrity Master antivirus program, and Nick FitzGerald, editor of Virus Bulletin.