This sort of error can be caused by a few things including uninstalling software or running a disk or registry cleaner inadvertantly.
Usually you can replace lost .dll files but i cant seem to find this particular one anywhere and i am not familiar with it.

I guess this leaves you with a couple of choices,
(a) You can perform a system restore if you have it activated in windows or,

(b) You can boot from your install disc and perform a repair install of windows.

Regards