I asked this question quite some time ago, and since that time I have undertaken a number of things, including a re-format. But things have now returned to a problem state again. So I hope further help may resolve the issue, once and for all.
Use computer daily, with Firefox and Internet Explorer 8 as the browser's. During usage, everything seems to be running fine, then suddenly the system appears to freeze with a 'Not Responding' error appears on Cltrl-Alt-Delete check. Transferring to the other browser, the same problem occurs, with the end result that I need to re-boot, and start from scratch.
The computer as all the 'normal' software, which as been on the computer for ages, and all of this seems fairly compatible. I am now wondering if an internet connection via the ISP can be the problem or whether its something else. Recently we have had power failures on the grid, but I cannot see that this is the problem.