Hi. I must have been infected by something. Yesterday I did a chkdsk on my c: drive. It ran, found some corrupt files, etc. Then when it finished, when windows tried to start, I got a win95-era popup window that said:
"lsass.exe - bad file; The attributes of the specified mapping file for a section of memory cannot be read" I click ok. Computer restarts, windows loading screen, same window. So I force-shut down the computer and that's the last thing I did before now. On looking up this error online, I saw some suggestions to do a repair install, which I have not personally done by myself.