Verified answer

Go to the link below to find a direct link to the user manual for this switch. Chapter 4 outlined the command you will need to reset it to factory setting.

Reset 3com Switch

The best option would be to clean it up - uninstall programs you don't use, clean out all temp files, scan for malware, etc. If your computer did not come with a disc, then you most likely have a recovery partition (D drive) - Start>Programs>System Recovery, or at startup you would see a message to press F10 or F11 for recovery. This would reinstall your o/s to factory settings.