When do my ads stop running?

Try HERE  http://adwords.google.com/support/bin/answer.py?answer=59386

And also, with a small budget, you really need to look for keywords that are going to trigger conversions. It is essential that you use longer keyword phrases. It might take some time to reduce your list and really get a strong list of keywords, but it will be worth it.

Try running a Search Query Performance as well....this will show all the searches that trigger your ads. I use this list to create a NEGATIVE keyword list for my campaigns.

Thank you for the advice - I have turned a whole campaign around using more specific keywords, but I am still concerned that my ads are stopping in the middle of the day. Maybe I am just paranoid, but I would like to have something that tells me.

use the scheduling feature to only have your ads show when you want them to. I use analytics to look at when i get most of my conversions, and then just run my ads then.