Grub2 problem

Grub 2 in Debian Wheezy, MBR, multiboot.
1. Grub started not with my customized look but with default big reso and look.
2. or it skipped conf and went stright to 'grub' prompt.
3. but approximately only in a half of starts.
4. and there was marked delay in Grubs' menu-loading.

What it means is - Grub couldn't find its config file(s), sometimes.
And, in this case, that there is some intermittent issue - appearing and disappearing. I have to say that such kind of behaviour was new to me. In almost three years of various linux installs etc I never met such kind of inconsistent behaviour - things either work or not...

Solution is simple: As we are talking about Debian, then it's 'update-grub' you wan't to run.
And that's it. Loading lag disappeared together with inability to load confs...
So, something got corrupted (and it didn't show in file dates in any way)... Fortunately it also uncorrupted itself in a simple way.