Unknown virus?

[batat]

1. Czech forum doesn't work
2. I think,  that my computer is infected(50%). I am running on MS Win XP sp2 (fully patched)  I use avast 4.5 home, virus database 0503-2. I am downloading updates daily.  Also I use MS Antispyware,  Spybot S&D, Ad-adware SE. All test are negative but!
Symptoms:
Objective:
Some files can't be deleted (also mp3)
Sometimes process explorer.exe took 99% of CPU load/time
Analysis:
No unknown process loaded (according to task manager).
Files can NOT be deleted also in safe mode (núdzový režim)
Files can be deleted from DOS/Linux (I'm running on FAT32)
So my disk is OK.
Conclusion:
?
Do you have any ideas what to do?
Thanks for help.

[Lisandro]

Files can NOT be deleted also in safe mode (núdzový režim) / Files can be deleted from DOS/Linux (I'm running on FAT32)

Are you sure the attributes of them are not set to 'read-only'?
There are DOS commands for changing the attributes.

So my disk is OK.

Do you mean 'scandisk' said nothing about troubles?

Can you run a scanning into safe mode?
Can you run a boot time scanning (if you have 2k\XP)?

[batat]

I AM LAMA!!!!  And I am Lama FOR EVER :'(
It was really marked as READ ONLY. But it used to ask if I really want to delete files marked as read-only and not to refuse delete it.
It is behavior of SP2 for XP, isn't it?
My many thanks to you.
P.S.: I am sorry for my bad English

[batat]

One more question. Who marked it as read only? It wasn't mine

[Lisandro]

Some files can't be deleted (also mp3)

Can you say the name of the files and their path?
Maybe we can help you more.
Don't worry about your English. We can understand it perfectly 

[batat]

For example:
G:\mp3 (all files including directory)
C:\cygwin (all files including directories - maybe not all, but you can't check them all)
P.S.: I don't know if it helps...

[batat]

Eh, problem with explorer.exe process is still here. Sometimes, when I close some programs (Orbiter - spacecraft simulator,Nero) or open (Total commander) it use 70-90% of processor time. It takes aproximately 10 minutes. After that, all is OK again.
Yeah, I know, nobody knows whats wrong...
Never mind.  I'll reinstall Win in next month...

[Eddy]

Let us have a look at a HijackThis log. It may tell us more about what is going on.
Also have a look at your system and event log files.

[batat]

I'll check  it.

[batat]

Oh, folder containing rar files (comprimed film)  marked as read only and can not be unchecked!!!
In fact, I uncheck this option. Then I close that window. I reopen it and it is checked again!!!