Just for confirmation you didn't say directly(option to "optimize your PC" suggests to me you have used the paid rather than the trial however) you paid for the product - i was interested enough to find out (what turned out to be the) trial will give you the problems but you have to pay for the program to fix the probs itself (i intend to to do the fixing myself from its results but some of what it might see as problems I wont on my set up).
Sorry I only have obvious suggestions i guess you would have already done it if you could - 7's System restore?(Xp's is far too maligned from my experienced and it has saved me from problems i just cannot find a fix for) - are you using it or any other software to go back in time/undo what grimefighter has done?
As i said about my personal PC requirements its all relative, neither of the other programs you used to check the system fro probs use anymore in absolute terms than Avast (AV have to have 'more' absolute terms to agree on) + i could see from reading about what the characters do some was OTT for me but then you would need experience/knowledge about an area to know what would fit your set up etc. From what I've read on the Avast site Grimefighter includes endless years of my knowledge gained from over a decade worth of windows experience which is good if you haven't got my experience but bad if it goes wrong - BUT THE POINT IS it SHOULDN'T and cause you more problems just fix ones.With my experience i dont easily recognise "cant find a valid copy of windows" (except for when booting into 7 not actually in it when active) - it sounds bad (NOT that is is) - has it effected your license activation of Win7, does grimefighter like avast have millions of settings + one has one gone awry - is/was it no longer set to the right letter/directory it was set with?Sorry for the obvious one is your Win7 professional still i assume as previous the "C":\ drive when you are actively booted into it?
re boot problems.(not sure when you say 'it does reboot back into 7" perhaps grimefighter has/makes a separate bootable environment (not had chance to try it yet - in which case perhaps Seven became,seemingly randomly imo, in booting terms is called a "hidden partition" you cant see it from explorer when you boot into another environment (a bit like the NOTORIOUS for causing probs, drive letterless,hidden "System partition" usually installed with Vista/7,) it can automatically UNHIDE when you boot into it, if not (self booting or not)endless boot software including 7's cmd based diskpart.exe ) can unhide a hidden partition) are you familiar with M$ own automated boot repair tool for 7/Vista - you might have an option about "repair" in your boot menu Professional definitely has a "7 System Repair disc" making facility - that's makes a DVD (+ what you can make from that DVD to boot instead etc) you boot of,f starts off with the boot repair tool (plus other manual tools but NO GUI), However you mention Win7 is booting fine now - generally boot problem prevent you from booting the OS.
hope some of my ideas are understandable/worth your time reading it.