my laptop got a virus, but I can't figure out how....

[theGlove]

ok seems like my laptop got the autorun/ls trojan or something like that. Basically it removed access so that I can't bring up any admin stuff like the registry, task manager and can't even logout/restart except by physically pushing the shutdown button.
I think I got it fixed thanks to antivir but I can't figure out how I got the virus. I didn't click on any emails etc.
There are 2 possible ways I think I may have got it, but I'm not sure if it's possible. Can you get a virus just by logging into a wireless network? Also, I did transfer over some jpg files from another computer onto the laptop (via usb card reader). Could that have trigger the virus? thanks

 

[John]

Old versions of java, quicktime, and flash are exploited, so be sure to remove old versions and visit Secunia.com to run the software inspector. You also need to keep the OS updated to avoid exploits. Even legit websites serve up malware thru ad banners.

Read more....

 

[mechBgon]

Also, yes, malware routinely infects USB/flash drives & devices. If it would work for your needs, consider using a non-Administrator user account as a containment measure against a big swath of common malware.