I have a file with song lyrics, about 120 pages, 284K characters, file size under 1MB.
When I start Word, [10,324MB application file size] nothing is too bad; it takes up about 1.3MB minimized, 10MB as the active application. When another application is active, Winword.exe uses 70%-85%, though it is sitting there doing nothing.
I can open a .txt version of the data file & memory goes to about 10MB, and CPU time is at most 5%.
If I open a .doc version (originally it was .doc, but when I saw this problem I converted it to .txt to eliminate any possible macro virus & checked the contents) created by changing the .txt to .doc again, the memory used goes to 25MB, and CPU time jumps to at least 85%, & mostly 100%.
Scrolling through the file causes the % to DROP [opposite of scrolling any other file], then goes back up - and selection of any menu item causes it to drop too.
More strange - I just changed the font from Times New Roman to plain text. CPU% went from a solid 100% to varying between 50%-85%, then I 'undid' the action & % went back to 100%.

Now I doubt this was happening last month - I saw nothing to point me to the CPU getting tied up. Noticed it today when I could not get control when loading a web page.
I have tried a re-load of Word from the CD, even destroying the Winword.exe file so I know it was re-created (a problem a few weeks ago proved that requesting a repair install with over-write 'no matter what' does not over write all files -- see XP Theme gone in this catagory).
I plan to un-install all of Office, then defrag & re-install, but want to hear from others about possible causes first.
Running AMD Sempron 2300+ (1.53GHz) single processor, 512 MB DDRram, Performance Options set to 'Programs' for both Processor & Memory, 4000MB virtual memory spread across drive 0 (0 on C:, 2GB on

) and 2GB on drive 1 (0 on G, 2Gb on H, 0 on I), available is 90GB.
At this point, I suspect something wrond with the hard drive [stay away from Maxtor 6B200P0, 200GB units]as a recent chkdsk seems to have caused the XP theme, & other, problems. DARN this MS

OS!!!!!