I don't know if you have a heavily modified sim, but you could try this:
Rename you FS9 main folder to something else and then do a clean install of FS9 in a new folder with the same name as your old FS9 folder. If you have a default install it should be called "Flight Simulator 9". Install the 9.1 patch FROM WITHIN the main FS9 folder. If you don't do it that way you WILL corrupt some dll's.
Install the bloom effect files right after you've installed the 9.1 update and see how it works out.
Now move and/or reinstall every addon you've had installed in your original sim back to the new installation. Generally you shouldn't have an issue with aircraft or scenery addons that you just move from folder to folder. I think the issue occurred when you (possibly) used an auto-installer, check after every time you've added something if you still have an issue with the bloom effect.
Let me know how it works ...