battery issue?

Using WinXP on a 6-year-old Dell Precision 4300 laptop. I had the
battery replaced a few days ago when it wasn't charging properly.
Everything was fine until I took the laptop back yesterday to have it
blown out and the fan checked (first time ever). Since then, the taskbar
icon that shows the battery being charged is constantly on instead of
reverting to "AC Power" when it's finished charging. At first it was on
even when the battery was charged 100%. I unplugged the machine long
enough to let the battery discharge a bit and then plugged it back in.
Now it's claiming to be charging all the time at 99% charged.

Any idea what could be causing the problem? And, even more important, is
it dangerous? I called the repair place, and the technician I talked to
said that probably a signal was being misread and it wasn't a problem.

Thank you,

Jo-Anne