Applications on my MacBook Air keep crashing

Question

Hi,
I have a mid-2012 11-inch MacBook Air, with Mountain Lion installed and all software updated to the most recent versions.
Over the past few weeks, I've been dealing with an increasing number of crashes among open applications (Safari, Mail and Skype), whether they are active, in the background, hidden or minimised. Lately, whenever Safari crashes, it takes around a minute to start loading up web pages properly. I'm not sure how to fix this - I've tried running Disk Utility and it reports no problems. I have Avast! and it repoorts no infections (though more than a few warnings of corrupted files).
Any suggestions as to what could be causing this, or how I might get around to dealing with it?
-C

Answer 1

I wasn't clear, I meant utilities such as menubar items or other types of add-on (SIMBL, for example.) The other thing to consider is that something is corrupted that is causing the crashes. Consider setting up a new user account with admin privileges. Log into this new account and see if the same crashes occur. If they don't, then there's a problem with one or more things in your normal user account - preference files, temporary files, cache files, for example.)
And, I can't urge you enough to uninstall the AV software. Avast should have an uninstaller to use.