I used disk cleanup as one of my maintenance scheme. As it calculates the amount of space it can regenerate by deleting files, it showed a tremendous amount of space amounting to 116 GB in the "Per User Queued Windows Error Reporting" section.
Heres the screenshot:

http://img174.imageshack.us/my.....nupiv0.jpg

The question is, Is it safe to cleanup?

Oh thank you very much jd! This is a great help.

I think this disaster has already happened to me. After running Disk Cleanup, while just thinking that the 147Gb size given for some kind of 'error log' file (don't remember exactly), it seems to have done some serious damage. After restart, I got message 'Windows did not shut down properly' so I selected Safe Mode. Lenovo Repair came up (I have a Lenovo T61, bought in Feb 2008 with Vista) so I ran the 'system will not start' repair. It finished after about 20 mins and then I restarted.

I'm now running System Restore (but the only one to choose from (there should have been many) was the one created by Disk Cleanup itself before starting the 'Disk ****up' operaton. It may be OK, but I had to go out somewhere so after about 20 mins I left it running while it was still showing the 'System Restore is initializing' screen.

Anyone had a similar experience? Successful or unsuccessful recovery? If unsuccessful, what would the forum recommend as a solution. I guess I could reinstall Vista as a last resort as I do have a recent backup of my personal data. But this is QUITE SHOCKING...something as simple as a Windows utility should NEVER exhibit this kind of behaviour. I work in the IBM Mainframe world - this kind of thing hasn't happened to anyone in the world in the last 40 years to the best of my knowledge - how is it possible for Microsoft products to be so bad?

Thanks for reading.

Hey guys, that's why I keep saying: Leave the system alone. It can very well take care of itself. All this puttering around really does not help.

Surely Disk Cleanup is supposed to be a safe application? Is it now necessary to search the Web for possible problems before you run any Microsoft application? I don't think using something that Microsoft supplies for the specific purpose of freeing up disk space can be considered 'puttering'.

However I have now got my system back but not after a tricky problem that might warrant a topic on its own; the Lenovo ThinkVantage 'System Rejuvenation' process appears to corrupt the Vista product license key after the first forced restart (that was the Microsoft tech support person's theory) - I could not log on to Windows because when it asked for the license key to activate Vista it rejected the correct key that I entered (printed on the sticker on the laptop). But the problem was fixed after a long phone call to Microsoft this morning - involving another System Restore from Safe Mode which picked up the Restore Point made before the first step of the ThinkVantage recovery process, which then enabled the ThinkVantage recovery process to complete.

So now I'm back to a system backup about a month old and all I have to do is reinstall the small number of applications that I had installed since then. And I did make a back up of my personal data on July 1 which is not the best but better than nothing.

However, a further caveat on the Disk Cleanup process - if it goes wrong due to the problem reported in earlier posts it also wipes out all the existing System Restore Points and the one it creates itself doesn't work. If I hadn't had a ThinkVantage system backup then I might well have had to reinstall Vista. Of course, if I hadn’t checked those little boxes that promised to free up 147G of non-existent space…… So I’ll take that as my Microsoft lesson for today – if anything looks weird I won’t do it without searching for an explanation first – like tan2x was wise enough to do.

As I said before. That problem seems to have gone when SP1 arrived.
And if you have done it (as have I (used Disk Cleanup wreck system)). Then no need to reinstall. The system is already factory restored by doing so!