Time Machine error

[baba]

Time Machine has stopped backing up my iMac. I have gotten this window every hour for the last two days:

 

[g/re/p]

What/where are you backing up to? An external disk?

 

[baba]

I'm backing up to a Time Capsule, but I think I may have found a problem. I had a non-asci symbol in the name and it wasn't recognized. I am attempting another backup now, having renamed the backup disk. Thanks for the response.