I had same work with an old PowerBuilder 8 application maintenance and upgrade. While trying to add OLE control to a windows PB constantly crashed. PB and Windows XP reinstall didn’t helped. I found a hint here http://brucearmstrong.wordpress.com/2007/07/10/problems-using-activex-controls/
1. Download Process Monitor
2. Add filter to pb80.exe process and path that begins with HKCR\CLSID
3. Try to add OLE with PB (make it crash)
4. Find last entry that ends with Control, search this CLSID with regedit
5. Reregister dll You found.
In my case it was regsvr32 %systemroot%\system32\mstscax.dll