Installer on Windows 7 crashes

[forcage]

Hi, on my Windows 7, the installer (Virtualbox-*-Win.exe) consistently crashes at the point when I try to change the install location by clicking on the Browse button.

The last version whose installer does not crash is 4.2.16 which I removed before trying to install newer ones (the reason to upgrade was that obviously some windows update broke the path browser functionality, it crashed when I tried to select a new CD image to mount, although I could select the previously remembered ones).
I tried to install 4.2.18, 4.3.6, 4.3.8, they all crash in the same way in the installer.
I also tried removing the network interfaces that VB created and rebooting the machine.

The system is Windows 7 Enterprise SP1 32 bit, 2 cores, 4 GB RAM.
From the possible conflicting software I found on the forums, I have Cisco Anyconnect client installed but not in use and its service stopped.
I also have Dropbox (stopped), McAfee OnAccess scan (disabled).

No log file was created near the installer exe.
The installer left a VirtualBox folder in AppData/Local/Temp, with a common.cab and an msi file - apparently it had no chance to delete its temp files.

The event log contains Event 1000, ApplicationError:

EventData:
VirtualBox-4.3.8-92456-Win.exe
4.3.8.0
530cde0f
KERNELBASE.dll
6.1.7601.18229
51fb10c6
c06d007e
0000812f
2194
01cf346947f68af0
D:\sw\Virtualbox\VirtualBox-4.3.8-92456-Win.exe
C:\WINDOWS\system32\KERNELBASE.dll
88b81ad2-a05c-11e3-b449-20689d5d8034

Can anyone tell where to look next?
Thank you.