I'm running Excel 2010 with Windows 7 64-bit and am constantly getting the "No more new fonts may be applied. Please close some other documents and try again." message. It's happening on various spreadsheets at seemingly random times. I'm not doing anything with charts (I've seen some other posts online regarding this same error message where people were copying charts) or macros or anything complicated like that. I am doing a fair bit of copying/pasting and playing with fonts/colors/shading, and have a handful of sheets within each file, but that's about it. When the message appears while I'm working on a specific file, I am able to work on other spreadsheets. In other words, the error doesn't affect all my Excel spreadsheets at the same time. My google searches have yielded a number of hits for other experiencing this same problem, but no solutions that apply to Excel 2010.
Thanks in advance for your help!