[Plugin: NextGEN Gallery] Photo upload not working

I am using NextGEN Gallery 1.9.1 on MacOS 10.7.2 using Safari 5.1.2.
When I try to upload a photo (with or without the Flash interface) I get an error message saying their was a failure, ID 313. And the following error message: (Error : Exceed Memory limit. Require : 66.02 MByte). The file I am uploading in only 1.8 MByte.
It had been working with no problem up to there.
Thanks for your help. Alan.