Steps for using the compiler after a module install. Clear the Magento cache, enable compilation, recompile and then clear the Magento cache again. There’s so much cached stuff that it’s easy to end up running a mishmash of old code and new code, leading to your website failing anywhere from humorously to disastrously.
If your website still has problems with the added module, then…
The compiler is kind of a kludge hack and third party modules have to be written to work with it. Check with the people who produce the module to see if they have a later version that has been programmed to work with the compiler or if there are adjustments that need to be made so compilation will work.
If there are no fixes and the site will not work with the module and compilation, you have a choice between using the module and using compilation.