Googlebot is looking for strange urls, and mod_rewrite troubles

[unni]

Googlebot is looking for strange urls like

uoymjziyzrvup.html, ijizguzx.html, jglvdmbpyozsizf.html

This is happening to my php sites. Mod rewrite was not configured properly so insead of a 404, it was returing some files even if user typed a non-existing url. I corrected this problem few weeks back. is there any relation between these two problems?

Also in my another html site googlebot is looking for main directory files under sub directories. For eg my www direcotry contains files and dirs like

file1.html
dir1/
dir2/

Googlebot is looking for dir1/file1.html, dir1/dir2/

Please help...