We've switched from SP4 to SP5; now I want to check for a few gotchas.

First, the move from SP3 to SP4 was done without checking the runtimes on user side, and they were running SP4 executables on SP3 runtimes for quite a while. Not that anything bad happened... but then there were some glitches recently, where some things would run fine on one workstation, and bang inexplicably on the other, but not each time. Rather elusive stuff, and I wonder how much of it can be assigned to this SP discrepancy.

Now that we've just prepared a setup for SP4, we're moving to SP5 - so most of the users are still on SP3, the exes will be on SP5, and I got two questions: what's the risk of running exes this way, and exactly which files in the installation need to be refreshed in order to have a good setup. The guy who does the setup is not here, and won't be for a while, so please bear with ignorant me - I never had to learn that part thoroughly (InstallShield, I mean).

TIA