Excel Playing up

[bill351]

Hi Guys n Girls I have a strange problem that I havn't seen before, Firstly background info this is happening at work and our systems are XP Professional 2002 Service pack 1, Excel 2003 and Explorer 7 all of our info is based in a central HUB that we access through U:Drive All the worksheets in question are very basic no indepth formulas or any macros, it started about 5 months ago and has progressivly gotten worse, initial problem was " Microsoft has encountered a problem" I would normally have 4 or 5 workbooks open entering data very straight forward and have them close . Our IT guys have over the past months installed a different PC., Updated to Service Pack 3, Excel 2007 and the last Explorer 8 and have added extra Ram to the PC. 3 weeks ago everything was good no errors and everything was quick and stable and last week I had my first "Microsoft has encountered" and is progressing, Today I had all sheets open to see if I could track a particular sheet and I went to save a workbook I was working on and the sheets started flickering (like it was recalculating or refreshing over and over) and didnt stop so I went to the next sheet, which was stable and went to save and it started flickering too? I am at a loss as to what is wrong, Over the last 6 months our IT has been upgrading (our security I think) and the PC's has slowly been getting slower and slower,I feel this could be linked to the issues. I have been using these same spreadsheets for the past 4.5 years without a problem until now unfortunatly our IT do not know what the isues could be Please Help