problem with calcualting

[eggandbacon]

I hope that someone might be able to help me. i am using currently quite large spreadsheets, 10-20Mb with lots of formulas, vlookup, if statements etc, but i am having intermittent problems with the racalcualting. I have it switched off and press F9 when i want it to update, but sometimes it ays it is complete, but only some of the cells have been updated, and other times the calcualtion happens much too fast for it to have realistically taken place. Does anyont know why this is happening? i use Excel 2000, and have no errors with my formulae, I think, Is it the size of the file thats the problem? Thanks very much

[olasa]

About the file size. If the file is saved in 95/97/2000 file type. The files will be up to 50% bigger then if they are saved as only the 'Microsoft Excel worksbook (*.xls)' format.

Ola

[eggandbacon]

Thanks I checked that and it isnt the problem. The problem is that it just stops calculating.....