The problem appears to be with the config files.
Solution: I closed SE and in Windows Explorer, I deleted my 25.0.0 folder. Since I still have my 24.0.2 config files, SE copied these when I reopened it and the problem has gone away. . .for now
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Prior to doing the above, I did as PatrickKox suggested and exported my configuration using SE's Tools -> Options -> Export/Import Options -> Export All Options. After performing the steps in the Solution above, I imported my exported configuration and the problem reappeared. I then used Tools -> Options -> Export/Import Options -> Restore Default Options, but the problem remained.
Conclusion: (1) At some point in time, the configuration files were corrupted. (2) Once you have SE configured the way you want, make a backup of the My SlickEdit Config directory.
Thanks Patrick for the suggestions. I didn't know SlickEdit had an Export/Import Option. . .been doing it the old fashion way. . .close SE, compress config directory, delete config directory, reopen SE. This certainly makes it easier.