Not sure if this will help or not? Hope it does. Without more info on your problem I don't know what else to say, you can try some more tech related forums on the net for help maybe? Do you still have the problem when you unskin your system? If it only occurs when you use that skin then I don't think it is a problem with Rundll32.exe.
I'm assuming your using Win XP? So this applies to Win Xp only!
It could be that you have a missing or corrupted Rundll32.exe file. This issue may also be caused by a virus.
Make sure your virus defs are up to date and do a scan. (even if your not using xp)
Replace/Repair your Rundll32.exe by doing this:
1. Make sure you have your system disks. if you have a partition with this info then great.
2. Go to the start button and click on run
3. Type this in the run dialog box:
expand X:\i386\rundll32.ex_ c:\windows\rundll32.exe where the letter "x" represents the drive containing your I386 folder. e.g., win xp cd or partition containing setup info.
4. Hit enter
5. Reboot.
You may want to check your video drivers as well. If they got messed up it can cause a problem like this as well.
Hope this helps?