It will most likely not crash your computer but having two virus scanners run at the same time could give you more problems than you started with. Unless you want to stop using McAfee, I would not recommend that you install AVG Free.
To be honest, I think just clearing your browser cache and recent history, et cetera will solve your problem.. And it's very easy and quick to do;
It's under Tools -> Internet Options.
Read the description of each item before clicking "Delete". Decide if you want to keep any of them but I'd recommend cleaning all of it.. Make sure that you've got your passwords remembered.
If that doesn't solve your problem, we should look into this further.