No this is not normal. Have you run a full anti-virus scan?
Unfortunately, this problem can be caused by lots of things and can depend on what software has been installed.
The most usual cause, other than a virus infection, is that the Vaio is searching for links to software, services or drivers that no longer exist, have been moved or not fully uninstalled.
A software/driver conflict is another possibility as is a heavily fragmented hard drive or the system paging large amounts of data to the hard drive.
Two suggestions: -
1. Download a 30 day free trial of a Registry cleaning program to remove any incomplete or broken links. Run the utility to remove junk files. I would leave the hard drive defragmentation for now as this may take a long time to run on such a large hard disc. I am reluctant to recommend software of this sort as it can occasionally cause problems but I use System Mechanic.
Thanks very much for the helpful responses - I tried a restore as its new (only had it a few days) and the problem has been there from the outset . I was a bit reluctant , partly cos I'm not an expert and partly cos its new, to run new software in case I make the problem worse. According to my antivirus its clean (I should hope so, given that it is new!) I've now been given a helpline number by the company I bought it from which I'm going to try and see where we go from there. I'll let you and everyone know how I get on .