What does it mean when there is a yellow bubble on my toolbar saying i have a trojan...?

a yellow bubble appeared on the bottom right hand side of by screen saying that my computer was infected with a trojan, so i ran my antivirus and scanned the computer, nothing came up. what does this mean ?

What does it mean when there is a yellow bubble on my toolbar saying i have a trojan...?ducati

First thing is to make sure your anti-virus scanner is current, up-to-date with the newest dats, etc... everything below assumes your anti-virus is working as it should:

Second, It would help if i knew which "toolbar" you are talking about.

Let's assume for a moment you mean the lower righthand corner of the windows start bar.... (near the clock):

If the message was from your anti-virus program.. then it is possible that a trojan was found and automatically dealt with.. such as deleted or quarantined (which would explain why when you ran your scanner nothing was found, as it would have already dealt with the problem). Check the settings of your A/V program and see if you have it set to delete or quarantine. If quarantine, you will be able to see it in a special quarantined files location. If deleted, it's hopefully all gone.

If you were browsing a website and your Anti-Virus caught a trojan attempting to download... another place you should immediate look at and clean out suspicious files (not your cookies) is your temporary download folder... usually found at this location: