Error “Can’t execute the query because you have a conflicting read lock”

Blog was working fine last night, then just this morning when I logged into Admin I got the following error followed by a million lines of code:

[Can't execute the query because you have a conflicting read lock]
UPDATE wp_options SET option_value =

I get similar errors when trying to post.

I’ve cleared the cache, checked my options and saved them, but not sure what to do past that. Any suggestions?

Many thanks!