Windows 7 - Help please! Loosing drives and partitions

First my two DVD burners and blu ray burner were gone in Windows, then most of my hard drive partitions disappeared ...
BIOS shows the burners OK.
Partition Manager shows only C, D and E, and the rest as Unallocated (540Gb)....
Burners do show up in device manager but with exclamation marks "no driver".
What on earth may have happened?
No virus warning from Avast...

How did this come about?

I think thats why the OP is posting

This is true.

However, he denotes a series of events, and a timeline (is this over a couple seconds or days or restarts or months...) will certainly help us.

Very simply put:
- after startup this morning wanted to burn a data disk
- optical drives all three of 'em gone (ex m, n, o)
- exclamation mark in device mgr
- deleted in device mgr
- rebooted & checked BIOS: all present
- back in Windows 7 Ultimate partitions f, g, h, i, j, k and l gone
- and still exclamation marks
- started Partition Mgr: space now shown as unallocated

Hoping for some meaningful replies...

Hopefully I can get some data back from a backup, but how do I reinstall the opticals?

Hm, what motherboard are you running? Have you tried reinstalling your chipset drivers?

How many physical Hard Drives do you have?

When it drop these partitons, where exactly are the partitions located.

Meaning, if it is dropping say partition D and E for example, are those partitions on the SAME physical disk or different physical disks.

Is it random or always the same ones?

ALWAYS in a case like this, you should use System Restore to go back in time to a point before the problem happened. If that doesn't help, THEN move on to other options.

Good point. Easier to rule out if hardware issue or Software/Drivers.

Thanks!
Asus P5Q3-Deluxe-Wifi
If you say so, although the reason eludes me, I could try that, but isn't that something that's being installed automatically under Windows 7?
The only worrying thing I see in the device mgr are these damn three "!" marks...
I managed to get my data back from my external HD and filled it into newly made partitions.
So getting my opticals to work is the main concern now...
I tried installing Windows 7 just to have a peek (after first making an image of c:/) and sure enough they were found and installed correctly.
For several reasons I don't really want to do that, I'd have to spend days reinstalling my software, reinstalling my mixed network and last but not least reactivating Windows 7 Ultimate...