My son has a Lenovo Thinkpad x140e which we keep at the grandparents' house for schoolwork and light gaming, and we plan to take it away with us next month when we go on holiday. It's not been turned on since May, so last night I thought I'd bring it home, run all the pending updates, and upgrade it to Windows 10. Currently it's running Windows 7 Professional, SP1.

Anyway, I run the update checker. It just hung on "checking for updates". I stopped and started it a couple of times, and then it showed it had 74 updates pending, but it stuck on 0kb, 0% for ages, then just failed. After that it went back to hanging on checking for updates. After extensive Googling I have tried the following:

Ran the FixIt tool, which didn't appear to do anything
Updated the Windows Update Utility manually to the latest version for Win7 SP1
Ran the Windows Update Diagnostic, which wiped my "last update check" and "last updates installed" info in the update checker screen
Ran system check from the cmd prompt
Ran the Windows Update Readiness Tool 

At first the Readiness Update Tool also hung on checking for updates. I disabled Windows Updates in the services manager, and in the update tool, then renamed the Software Distribution folder, and tried to rename catroot2 but it said it was in use by another programme. I used task manager to ensure all that was running was windows explorer, but it still wouldn't rename. So I tried running the Update Readiness Tool again at that point and it ran, took a while, and installed a Hotfix to SP1. Then I turned Windows updates back on and it still hung at checking for updates. Ran the Windows Update Diagnostic Tool again and this time it did a lot of "resolving" before reporting that several things had been fixed, but one error could not be fixed: Windows Update Error 0x080070057.

I've Googled it, and not found anything suggested that I didn't already try. I assume I have a corrupted file in my registry somewhere causing this issue? I'm not particularly comfortable tinkering around in there, as the machine is running fine otherwise, and I don't want to bork it before we go on holiday.

Does anyone have experience with fixing this issue, or have any ideas about what I could do next? I am happy to try some registry changes if I have clear instructions to follow. Would I benefit from running a Windows repair? I made recovery media discs when I first bought the machine, so I assume there will be a non-destructive repair option on there somewhere (unless there's one in a separate partition I can run on the machine without having to muck around with external optical drives?).

I'd be really grateful for any help. I spent 5 hours on this last night and got really frustrated with it.