Sorry to hear about your bios issues that bites
I've never heard of a bios situation where you couldn't roll back ...
Yes I know it may seem strange but memory issues of any kind can stop the whole show before it ever starts.
It you have a situation where your bios is downclocking the memory thats not a bad thing per say , 1066 and 1006 is almost like saying PC133 downclocked to 100Mhz or more interestingly like saying DDR400 downclocked to 799.9
There exists the slight possibility that your power supply may not be strong enough
I say slight like 10% chance. it does look a little under powered for the hardware you're running. ( farther information and testing required on that )
I'm trying my best to offer you at least some thoughts on this because I sure get an uncomfortable feeling when there is hardware not working in the world some place.
( it's my paranoid schizophrenia lol )
This all could be because of an incorrect voltage to the memory or timming issues or voltage or just plain defective memory bit.
I realise you may not want to go through the head ache of running some Memtest86 or other memory diagnostic programs , but that may be the only way you can verify that the memory is working correctly.
It can seem like memory is ok and everything working when in reality the memory is not setup correctly
which reveals it's self in many ways such as a single program fails to operate properly while everything else is working fine.
Installing a program can poke the memory in such a way that it causes an error if the memory is not set up correctly.
( trust but verify
)
Keep brain storming , I'm here for you buddy