I get such an error when I open IE8 in Windows 7 32-bit machine:
An unhandled exception ( Unknown runtime error ) occurred in iexplore.exe 
and a Microsoft Visual Debugger starts up.
Any suggestions or help on this?
The Issue is solved. Might have been a possible problem with the third party toolbars and some addons. The issue stopped after I removed those toolbars and addons.
Probably one of BHOs (Browser Helper Objects) is causing this error. They are DLLs (COM objects) loaded by iexplore.exe into its address space at startup. Try disabling IE BHOs using WhatsInStartup.