Windows 7 guest is stuck as a tiny window

[CCJ]

I'm running Yosemite 10.10.5 as host, VirtualBox 4.3.30, and Windows 7 as guest. The problem is that the guest display area always appears as a tiny rectangle even though the surrounding window is full screen. I have installed guest additions, and this same VM used to display properly before I toyed around with resizing its parent window. Now it seems to be stuck at the impractical size I last scaled the parent window down to (see attached screen shot). I can't re-install guest additions (or do anything else requiring VM interaction) because the VM display is too small.

Any idea how I might fix this or at least find more information in logs (perhaps something regarding the display size that the VM thinks it should have)? I couldn't find anything in Settings that would indicate what the guest's intended resolution is, or anything else that looked promising. I thought turning off auto-scaling might help, but that option is always checked and grayed-out for this VM.

[brycesteiner]

When I have and this issue in the past, usually it's just a matter of pushing the buttons (host+F) a several times and windows works out it's problems. If that doesnt work you could make it a window you would be able to install the guest additions in safe mode.

[CCJ]

When I have and this issue in the past, usually it's just a matter of pushing the buttons (host+F) a several times and windows works out it's problems. If that doesnt work you could make it a window you would be able to install the guest additions in safe mode.

I tried host+F a few times, to no avail. Making the view a window doesn't help either; switching to scaled mode just stretches the tiny image and adjusting window size just shrinks the window to fit the tiny image. I can boot into safe mode without issue, and the display is the default small-but-readable display that virtualbox VMs usually have prior to installing guest additions. I re-installed the guest additions, but upon rebooting normally I found the tiny window problem was still present. This at least suggests that some driver that isn't loaded in safe mode is responsible for this odd behavior.

[CCJ]

I think I found a workaround -- if you boot into safe mode with the 'Enable low resolution video (640x480)' option, and then modify your display resolution from Control Panel, the next normal boot should size the display to the resolution you specified in safe mode. It still isn't as pretty as it was after I first installed the guest additions, but it is usable now outside safe mode.

[mpack]

The usual solution is to select a new display size (not the size it was previously configured for), and reboot the Windows guest. The idea is to force Windows to update the display size registry entry and then reboot. After the reboot you can resize again to the original size and reboot again.

My own take: either Windows itself or VirtualBox (or a combo) somehow gets the idea that the teeny window is what the user wants in the current display mode. Forcing a display mode change - with a reboot to ensure that the change takes - is what fixes the problem.