>Hi everybody,
>
>On my husband's laptop we're getting 'Operating system not found" when we try to boot the computer. However, this problem is not always reproducible. Sometimes it boots and it works for 20 or more minutes before displaying this message.
>
>Before turning this laptop to professionals do you have some ideas what can be at fault here?
>
>Thanks a lot in advance.


Lots of things could cause that.

First thing I would do is make sure the hard drive is connected well - that could cause intermittant problems easily. Pull it out and plug it back in.

If that doesn't clear it up, do a full system a/v scan. Make sure it checks ALL FILES. Make sure it is set to fix or delete any infected files (we just had a customer come in with an infested server - they swore their A/V was up to date - it was - it was set to scan w/o notification and to not do anything if an infection was found!).

If that doesn't find anything, Check your drive for errors using Check Now from the Tools tab of the properties sheet for the drive in windows Explorer.