The exception error you experienced in your first post. Is caused by Yahoo! Messenger.
Application Name: YahooMessenger.exe
So a clean install may help. The link I posted above contains "Yahoo! Messenger Cache Cleaner". Download that tool.
Uninstall Yahoo! Messenger via Programs and Features in the Control Panel. Then run Yahoo! Messenger Cache Cleaner as administrator. Restart your PC.
Make sure you've got all of the requirements/dependencies for Yahoo! Messenger. Download Yahoo! Messenger and install it.