I just noted some strange activity in Premier 2005. I have two client files using this version and often switch between them without a problem. For some reason I just saw that the program button in the taskbar showed one company while I was actually working in a different one. The file switch worked but QB didn't update the file name in the taskbar.
Working in the vendor list for 1099 prep was a bit of a pain since the 1099 Summary wouldn't automatically refresh nor would it accurately refresh when hitting the refresh button. Ex: I found some vendors who didn't show up in the 1099 list because their 1099 status wasn't checked. I edited the vendor, checked the 1099 box, closed and noticed no change to the summary report. Hitting refresh still didn't add the vendor in. I had to close the report and reopen.
I've never had this problem before and, unfortunately, doing this kind of flipping/checking/unchecking during 1099 prep is normal. I ran the update just to be sure and QB found no new updates to download so my guess is that these are bugs but watch out for them.