Suspicious program?

Solitaire

My PC has been acting up lately, particularly in regard to freezing and HDD thrashing. I didn't read a huge amount into it as both the PC and its XP install are getting long in the tooth at this point, and the HDD is virtually full to boot. However, downloading Minecraft addons means negotiating the horrors of Adfly, the Internet's favourite SUPER-AIDS delivery service, and sure enough my last few trips there yesterday were being red-flagged by a screaming Avast Although that means the uglies aren't getting into my system mercifully!

Then when I'm restarting the PC today I get a program or service that's messing about and refusing to stop cleanly at shut down. Not exactly an uncommon issue for me... except... not only is it not one of the usual suspects, its screen name appears to be "Laugh "

That can't be legit

Needless to say there's no way such a name can be Googled and return any meaningful result, so I'm wondering if something slipped past Avast... which thinks nothing is wrong. So peoples... how do I check properly for something it has missed?

cookie1977

Use the usual first off:
www.malwarebytes.org

try kaspersky antivirus/antimalware removal tool too:
http://devbuilds.kaspersky-labs.com/devbuilds/AVPTool/avptool11/

You made need to boot the pc into safe mode

Squaredude

Download malware bytes.It should do the job.
http://www.malwarebytes.org/products/malwarebytes_free