PC not detecting hard drive (Windows 7)

I've got a single machine running a dual-boot setup with Windows 7 and 8. I didn't set this up myself, and honestly, I’m far from being some kind of IT expert... The Windows 7 side is 32-bit, while the Windows 8 side is 64-bit.

I was running into an issue on the Windows 7 side where I couldn't get online because I was missing a motherboard driver—specifically for the network card. This morning, I decided to run the offline version of DriverPack Solution, which actually fixed the connection issue. But now, I've hit a new snag: one of my hard drives has completely vanished from view.

To give you the layout, I have three separate drives: C:, where Windows 7 lives; D:, where Windows 8 is installed; and F:, which I use for all my various files and data.

The weird thing is, drive F: shows up perfectly fine when I'm logged into Windows 8, but it’s nowhere to be found when I boot into Windows 7. Does anyone know a way to make it visible in Windows 7 without having to format the whole thing? I've already tried a few different tips I found online, but nothing seems to work...

Here is how it looks under Windows 7:



And here is how it appears in Windows 8:

I’ve pinpointed what the issue is, now I just need someone to tell me how to fix it. 🙂
For a couple of days now, my drive hasn't been showing up at all, but then yesterday I fired up the machine and this message popped up saying the driver had installed successfully and I could finally access it. A little window appeared telling me I needed to restart the computer, so I did exactly that, but once the system booted back up, the drive just vanished again...
It's clearly a driver issue. Would simply running Driver Pack Solution again be enough to sort this out, or should I go through the trouble of hunting down the specific driver for this particular model and try installing that manually? If anyone has a better way of handling this, please let me know... I really don't want to start poking around blindly without some solid advice, otherwise I might end up making things even worse.