Malware or windows problem?

Hi, there has been something seriously wrong with my laptop since yesterday, I suspected malware but I haven't been able to detect any.


Windows is extremely slow to do almost anything, and most programs will not run at all (often an error or exception occurs while loading). Also a message saying that my copy of Windows is not an official copy (or something to that effect) has appeared on the bottom right of the desktop a couple of times, though it isn't there right now.


Programs which run OK and at the correct speed (once loaded): Windows Explorer, Task Manager, Remote Desktop, Excel, FRST
Programs which run but are very slow/unstable: Opera, Advanced SystemCare, AdwCleaner
Programs which DO NOT run: Internet Explorer, Chrome, Firefox, Calibre, TSG SysInfo, MBAM installer


Attempts to fix so far:
Tried to boot in Safe Mode, but the problem is still present (with or without Networking enabled).
Scanned with Advanced SystemCare and Adware Cleaner but nothing detected.
Scanned disk boot sectors and hidden startup objects with Kaspersky Rescue Disk but nothing detected.


TSG SysInfo will not run, but here's the info about my PC that I could find:

OS Version: Microsoft Windows 7 Home Premium, Service Pack 1, 64 bit (Japanese)
Processor: Intel(R) Core(TM) i3-2310M CPU @ 2.10 GHz
RAM: 4.00 GB
Hard Drives: C: Total - 398 GB, Free - 167 GB; D: Total - 49.9 GB, Free - 852 MB;


FRST will run if you need the output from that.


It could be malware, but I don't get why the problem is still present in Safe Mode. How can I go about trying to fix it?


Thanks in advance.