For me this was helpful:
- open winamp
- toggle main window ON if necessary ("Alt-W")
- if necessary double-click to change from playbar to (what should be) normal window
- right-click on the remaining bar
- choose to see e.g. equalizer
- bar breaks at the bottom and shows remains of misplaced equalizer
- grab edges and resize
The new rectangle-information will be stored, winamp ist in normal shape again.
Hope that helps.