Platform Builder for Windows CE/Windows Mobile 5.0 & 6.0 expires after 180 days. Rather than reinstalling the whole thing every time, there is a workaround.
PB knows when to expire based on the time stamp of the file Etkremov.inf. For WINCE 5, and both WM5 and WM6, this is located here:
C:\Program Files\Windows CE Platform Builder\5.00\EtkRemov.inf
For WM6, it’s located here:
C:\Program Files\Microsoft Platform Builder\6.00\EtkRemov.inf
Delete this file, and then create an empty text file of the same name in the same directory. Don’t bother wasting time re-installing! That takes hours.