Look everywhere through your System Folder for more than one copy of the Times font. I've seen various configurations in clients' Fonts folders, most often there is an extra copy (or three) lurking in suitcases called things like "WordPerfect required fonts" or "Equation Editor required fonts" or "Illustration required fonts" or some such thing...
Feel free to remove Times from any of these folders--you only need, in fact, only WANT, one copy of Times open.
The difference in screen draw *may* be due to the fact that a Type 1 version of Times was installed, and you may have been used to seeing the TrueType version. If you dont' have ATM installed on your computer, the Type 1 version will look jagged on-screen when used at other than the supplied screen font sizes.
Please post back (or email me) if you would like more assistance than these few cryptic paragraphs provide.