Disappearing partitions and more...

This morning, after turning on my computer, I was to discover...

1. 'reboot' and 'shutdown' have disappeared from the Start menu. It's even greyed out in Task Manager.
2. Two of my partitions are not visible in Explorer (or any other) but they are there. Shortcut Icons from the programs on these partitions are also gone but, on locating one shortcut, I was able to run the program (?).
3. Restore will not 'restore'.

This really has me perplexed!?! I ran a full Norton virus check and then an 'onsite' Trend Micro. Nothing at all was found. TrendMicro ,also, did not pick up my E: & F: partitions! C: was not damaged in anyway (that's where my system files are). E: has my Office files and F: just has some 'junk', fonts, and font-related programs. The partitions jump from D: to G:...seems like E & F are 'hidden' because I can run Winword from it's shortcut (one of the few that didn't get erased) which is on the E: partition.

I've run Spy Sweeper, Pest Patrol, Ad-aware, Spybot and Microsoft Anti-spyware. I've run Hijack This. Have come up clean and nothing unusual.

I have never ever come across anything like this before and I don't know what to do.

Specifications
ECS
System Model: K7S5A
BIOS Version: American Megatrends Inc. 07.00T

Operating System
Microsoft Windows XP Professional
Version: 5.1.2600
Service Pack: 2.0
Location: C:\WINDOWS
PID: 76487-643-7213323-23220
Hot Fix: KB893803v2

Memory (RAM)
Capacity: 1 GB

Processor
AMD Athlon(tm) XP 2000+
Version: x86 Family 6 Model 6 Stepping 2
Speed: 1659 MHz

General Computer Info
System Name: THOMTEL
Domain: HOME
Time Zone: Pacific Standard Time
Connection: Workstation (standalone)
Proxy Server: None
IP Address: 192.168.0.3
0.0.0.0
IPX Address: Not Enabled


Local Disk
Total Capacity: 183.78 GB
Sum of Hard Disks: (C: D: E: F: G: H: I: J: K: L: M: N: O: P: Q: R: S: T: )
Used: 76.66 GB

Free: 107.11 GB

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Thank you...

= sgt =