Massive freezes

Sup crossfire :[[[[[[[[[

Since very recently, I've started having uber freezes for like 5 full minutes whenever I open my Windows session. I have a few widgets on my desktop also, Objectdock or something like that and TrueTransparency , that's about it.

Doesn't happen with other sessions tho, lolwut ?

I believe it's due to the fact I've downloaded and kept all kind of shit in 4 years and never formated :[

I have 2 HDD and they're segmented in 3, C:\ , H:\ and I:\

C:\ being my former HDD and containing Windows, is almost full, may this cause the freeze?

Oh the freeze also happen sometimes while browsing (I use Opera, guess it's the same shit with other browsers tho) or one time out of two when I listen to a .mp3 file thru Quicktime in a browser :[

Happened once while playing ET tho.

Seems I also have some kind of virus, have Avast atm and it always did the job till now :_(

I'm considering formating all my drives, thing is I have no idea where my former Windows CD is and cba downloading some cracked version, got any solution ?