ScCore.dll is a Photoshop dll that's involved with the scripting system.
As far as why Photoshop can't find it... I can't speculate, but it sounds as though it's been deleted or corrupted somehow. You might be able to recover it by reinstalling Photoshop.
I listed all the places ScCore.dll is found on my Windows 7 system in post 35 in the following thread, if you want to check all yours:
Since owning PS v1 I remebered that removing the preferences file and restarting PS most likely would fix odd quirky errors.
And indeed it did this time by moving the folder to my desktop and restarting PS.
It will build a new one on startup.
Unfortunately you lose any workspaces and personal settings like keyboard shortcuts you previously set up, but it usually is a quick fix.
Do a search on your C drive for Adobe Photoshop CS5 Prefs.psp to guide you there.
Clearing preferences often seems to be a corrective factor in Photoshop problems. Glad to hear doing so fixed the problem for you.
It always worries me when people have to clear preferences, since that means that some part of the process of storing preferences in file(s) on their computer isn't working right, and storing files should always be utterly reliable. In all the years I have been using Photoshop I haven't had to clear preferences to correct a problem, so I know it's at least possible to have reliable preference file management. But no two people use Photoshop identically, and people do use 3rd party add-ons (plug-ins), so it's quite possible something you have done that I have not has caused Photoshop itself to corrupt its preferences file(s).
It would be good to try to keep mental track of anything you may do/change/install/etc. prior to situations where you need to clear your prefs. It may well be something specific you're doing or using that is the root cause.
Yeah, I hate having to do it since I like things consistent in my looks, actions and shortcuts and have to redo them.
Not a biggie since I was able to fix with little down time but it was out of left field when it happened.
But looking back, I was doing an extensive image search on the web and could of well been a little evilness that found its way in somehow.
Thanks again for the assist.
This was the first time using the Forum and I am impressed.
Adobe has really got some great stuff going on these days and impossible to exist without it!