As noted in the documentation:
Changelog 5.3: dl() is now disabled in some SAPIs due to stability issues. The only SAPIs that allow dl() are CLI and Embed. Use the Extension Loading Directives instead.
If using PEAR libraries that try to load extensions, like Image_Transform which will try to load ImageMagik, and the "enable_dl" directive is set to 1 in your php.ini, you may end up with a hard to find error (white screen of death).
One "solution" is to change the enable_dl directive to 0 in the php.ini. It may have adverse affects if you are using php on command line that requires the "dl" function, but I think in most cases its okay.