Why

I'm posting this again, but there's no change in the situation. Still my firefox and ie are crashing every time I open it. And my anti-vir won't work anymore. I downloaded together with a music downloader, but after opening it, it just disappeared so I was warned. I checked the processes and nothing odd was found. But at the next start up, my computer started very slowly and my anti-vir didn't start up and there were a lot of processes missing (it almost looked like safe-mode). And there was something new: b.exe and mds.exe
I killed those processes, but nothing turned out.
Because b.exe started at every start-up, i searced for it and found it in the start up program list, I removed it from there.

Please help!

PS.
The dds does'nt work, it just quit immidiatly after opening it. And the gmer works just fine, till a sertain point. After a while scanning it just quits and no log is found anywhere.

So I don't have clue what to do.

Why

BUMP, please