Web-based scan of your computer for infections, from BitDefender.
In its favor, it's lightning-quick, free, and requires no downloading. The not inconsiderable drawback is that it scans for in-memory infections only (will not see dormant malware).
Good for a second opinion.
Quickscan landed on my computer without my asking; virtually stopped my computer by a conflict with other software I run and want to keep: Blue Coat K9 Web Protection. Used another computer to contact Bit Defender, was advised to disable the plugin on Mozilla. Now have my computer back, but cannot get rid of Quickscan popup window, which has moved from the bottom right of my screen to the top left, obliterating Menu, first tab, address bar etc. Asked BD for help to get it off my screen and out of my computer; no response. Tried BD Forum, was blocked from registering.