Since I'm responsible for an ERP written in Access (yes, a full ERP in Access 2003) I'm extremely apprehensive of anything that might affect Access on end user's PC's. Office 2003 SP3 doesn't disappoint. There are several known issues but they pale in comparison to the problems being reported in the wild. These include Access applications that simply stop working in SP3, design elements being corrupted, and subforms that stop inserting records. Scary stuff indeed.
Couple this with Microsoft having to release the Access 2007 runtime three times -- and it's still got problems -- and I'm wondering if they do actually QA this stuff before they release it. I had a friend who worked for Oracle who used to joke their testing consisted of "SELECT * FROM Emp. Looks good? SHIP IT!"