I don't know this error, but this dll appears to be associated with this product:
http://www.3ivx.com/
Do you have it installed?
Could you try starting iTunes in "iTunes safe mode". You hold down ctrl shift while starting iTunes. Does it start then?
Also could you try to start Quicktime. If it fails,describe what happens with any error message in full.
If Quicktime doesn't work go to your control Panel (classic view) and try to start Quicktime preferences. Give the full text of any error message.
I suspect that 3ivx is causing the problem. There are a number of codec packs that cause trouble with Quicktime although this one is not on my list.
What I normally recommend for the other packs is that they are uninstalled then quickime is reininstalled as follows:
Download the version of QUicktime that done
not include iTunes - it is not the default so watch out.
http://www.apple.com/quicktime/download/win.html
Remove Quicktime using the method for Quicktime removal here:
http://support.apple.com/kb/HT1923
When you come to the system32 folder you can delete any file or folder with Quicktime in the name.
This procedure is speculative in your case as I have no knowledge of 3ivx. Perhaps it would be best if your report back with the results of my various questions before trying it.