Shoutbox

It may be smiley central. Go to contorl panel> Add/Remove Programs> look for smiley central> remove.

Also look for any other slightly dodgy things under add/remove programs and maybe research them.

You can also try running some spyware/adware scans.

Try:

Microsoft Anti-Spyware (Beta)

Ad-aware SE 1.06

Spybot Search & Destory

EDIT: If this is to do with stuffplug, you will probably get a better reply to posting on the stuffplug forums at http://www.stuffplug.com/forum/