I believe this happening for two weeks now: Excel 2007 (on Windows XP) is acting funny on my computer; any medium sized sheet with some formulas in it takes a significant amount of time recalculating. I can see this because the "calculating: 2 processors xx%" message was almost unseen before and now it appears on most operations like calculating a formula (on one cell), saving, previewing, etc. If the sheet is complex (lots of formulas) I have to disable automatic calculations because excel renders as unusable - it hangs for a really long time, measureable in minutes. Any idea on what may be causing this? ps: this is a Core2 Duo computer with 2 Gb of RAM