I am using v550 on an XP SP3 machine and a Vista Home Premium machine. I find that the Software Uninstaller is inconsistent. I have been using jv16pt for some years now so I'm relatively familiar with its operation. Getting back to the inconsistency, it seems to work on some programs but not others. Specifically, it will not remove Adobe Shockwave. This has been happening for a couple of versions of both jv16pt and Shockwave. Since jv16pt has been in flux, I've just been waiting for a fix but I thought I'd speak up now.
Typically, I use Add/Remove to uninstall software. Then I run jv16pt Software Uninstaller (I like Software Manager better..<grin>..) to remove any leftover threads as well as any related 3rd party threads. Finally, I run the Registry Cleaner to remove any leftovers.
As noted above, Software installer works most of the time but it barfs on Adobe Shockwave v11.5.0.595. Same-same for the previous version of Shockwave. The uninstaller starts (bar meter appears) and then it stalls. I've waited for 5 minutes for it to complete and it doesn't.
HOWEVER, if I skip the Add/Remove step and use only jv16pt Software Uninstaller, then the Software Uninstaller works. In that test, when I clicked on Uninstall, the Adobe remover popped up momentarily and then the Software Uninstaller meter came up and completed.
I also tried using Software Uninstaller *after Add/Remove) to remove the last traces of Adobe Reader v9.1 with the same stall. Hence, it may just be the Adobe stuff that is barfing Software Uninstaller.