Uninstall or upgrade on Win7

[genuap]

I'm trying unsucessfully to uninstall VBox 4.1.10 on a Win7 32-bit machine.

I don't get an error, however when I run the uninstaller, it pops a window showing percentage complete, with,a bar moving from left to right. It suddenly moves right to left. And then exits. No error.

I've tried to reboot after, but VBox still shows up on my start menu. And I can still run it.

Any idea where I can look for a log or a reason why this doesn't work?

I'm trying to uninstall, because upgrading VBox doesn't seem to work for me either. When I try to upgrade to 4.2.6 it seems to run the installer, and then suddenly rolls back action, and completes with the bar moving right to left. Error message when upgrading is:
"Oracle VM VirtualBox 4.2.6 Setup Wizard ended prematurely"


No idea why either of these isn't working.

Thank you.