This is how it happened, I installed some driver and my computer showed following error .

RTHDCPL.EXE - Illegal System DLL Relocation

The system DLL user32.dll was relocated in memory. The application will not run properly. The relocation occurred because the DLL C:\Windows\System32\Hhctrl.ocx occupied an address range reserved for Windows system DLLs. The vendor supplying the DLL should be contacted for a new DLL

When I close it, nothing happens but on every computer start, it comes again .. can I ignore it ?

Its an old issue, its with microsoft sp2 updates, just do updates once more and after that it will be resolved automatically. In short make sure computer is upto date.

Re-install your sound driver...

you seem to be using Realetk HD audio 5.1 or 7.1 Onboard.

I have onboard audio, I reinstalled driver but no gain. I will try to update it today and then post results here.

What windows you are using?

There are some issues with vista...

Just keep an eye on latest updates.
Thats the driver for Realetk HD audio 5.1 or 7.1 Onboard.