It sounds like a Windows registry corruption and you may need to reinstall the operating system on your computer. In the meantime, please try updating to the latest graphics drivers at http://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=9033&ProdId=865&lang=eng&OSVersion=Windows%20XP%20%20Professional*&DownloadType=
Additionally, please bear in mind that Intel no longer provides assistance for your graphics controller, If you are interested in additional information see below:
Thank you allan_intel for your kind assistance.
I think I had the latest Intel® Graphics Media Accelerator Driver, but downloaded from your link in case.
I then restarted the computer as prompted and opened the Intel(R) 82845G/GL/GE/PE/GV Graphics Controller and the screen resized and off-centred.
I again thank you for your time and help and hope your days are many and filled with joy.
just to let you know that I have made some progress in resolving the problem - in case it may help anyone else- by doing as another helpsite suggested and replaced my CRT monitor , with an old LCD one and the problem disappeared....... so I guess that it was my CRT monitor.