Windows 7 - Occasional non-starting apps

I am running Windows 7 Pro 64-bit. Sometimes, I start my system and, when it's fully up, click on an app (eg Firefox, Outlook, Word, Excel etc) in the taskbar as normal but sometimes they don't start - the timer shows then, after 5-10 secs, it stops & the app fails to open. None of them will open until I reboot. This seems to suggest a Windows, rather than installed SW, problem. It's happened on and off for some months now so I can't pin it back to some change in the past...
Any tips on how to diagnose - where would I dig out error reports for these events, if at all? Thanks!

Hi all

No-one else seen this? I have it on my laptop. My wife's also occasionally (she runs Win Home Premium).

Grateful for any ideas / thoughts...

Thanks!

Hello John,

You have to know that that is a very general problem. So general in fact that the fastest way to solve it would be to completely reinstall the OS.

You might try these:
SFC /SCANNOW Command - System File Checker
Startup Repair
And if those don't work, this one: Repair Install

Aside from that, try to see if there is something installed on your computer that may be causing this problem. Even the antivirus (there are some bad ones out there) can cause such problems.

And then there is the clean install, 'sure fire' method: Clean Install Windows 7