What OS is your server running?
As far as the 'directive' it's talking about, check in your php.ini file for a 'browscap' directive. Here's the section in the original php.ini:
[browscap]
;browscap = extra/browscap.ini
All you have to do is uncomment that line and set it to the correct path (e.g. c:\windows\system32\wherever-this-file-is\ - I can't remember where it is at the moment).