Error message...."Loading of one or more plug-in files has failed.The plug-in files might be either corrupt or not valid."

Win XP, Photoshop 7

I don't know what's happened here or how to fix it. I opened a picture, increased the image size to 300ppi, saved as a different name in order to keep orginal, filed as a jpeg. That's it. I was able to do this successfully to 4 pictures and then something went wrong. I have restarted my computer. How do I fix this? Please, please help! I'm trying to get these pics ready for print... for a gift. I need help asap!

Thanks in advance for any help you could offer!!!!!!