My initial thought when seeing your FRST log was that your machine had a conflict going on with the security programs you have. Running two or more real-time anti-virus, anti-spyware and firewall monitors at the same time can cause a conflict. That conflict can result in slow computer performance, error messages, crashes of the programs or other types of failure. Also, one of your programs was Avast which had a conflict problem recently with a Windows update. For that reason I endeavored to remove the active parts of Avast (we would reinstall it later if needed although you appear to have Microsoft Security Essentials on your machine as well). So far we had no luck with that although at one point it did seem that we were making progress.
When that didn't work I consulted and opinion was that, yes AV conflict seemed the most likely cause but that we should discount hard drive or memory problems. You didn't have much luck with the Lenovo support center but when we ran chkdsk it did pick up bad clusters which denotes problems with the hard drive eventually leading to failure. Exactly when that might happen I don't know and might be something you could take up in the technical forums.
Having said all that, if it were me, and seeing I had a back up, I would go for a factory restore and see how my computer performed after that. Always remembering that your hard drive might be on the way out and the long term solution would likely be a hard drive replacement or a new computer.
Question is how to do that if it's what you choose.
There are a number of options available to Lenovo owners depending on the model they have.
Here are two links I have found that may be of help:
How to use the pre-boot service partition to recover your software. Does not apply to all Lenovo's but worth checking to see if yours applies.
How do I recover my factory installed programs and files? Quite a bit of reading but may be helpful if the above link doesn't apply to your machine.
Meantime you could try running chkdsk again sometimes it needs to run two or three times to do the job.