Registry issue

When I use the following line as part of an install:
WriteRegStr HKLM SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce "WSDialog" "regsvr32 scrobj.dll /n /i:file://C:/$INSTDIR\wscProgressDialog.wsc"

If $INSTDIR contains "Program Files" (As selected by the end user), the registry ignores the Program portion and just uses "Files". Does anyone know how I can rectify this?

Try quoting.

The directory is provided from the $INSTDIR variable via the end-user. How do I quote it?

Just add quotes around the path in that line:

WriteRegStr HKLM SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce "WSDialog" 'regsvr32 scrobj.dll /n /i:"$INSTDIR\wscProgressDialog.wsc"'

Thank you!