Hi Mike and Robert --
Thanks for sending in this message. Our team knows about the issue and we have several people on our team working to make sure this is back up to the stability you need and expect. We had no stability problems with our Java servers last year, but at the start of this year we've seen a huge jump in hundreds of thousands more programs run than we had anticipated. We target about 97-98% programs run successfully and this was what we had all of last year, this last week has dropped significantly. We're working on fixes now and should have an update for you soon.
In the meantime, it still is the case that a large majority of programs should complete as normal - the best thing to try as a stopgap is refreshing the page and trying to run the program again.
I am sorry that you've been having trouble with the performance of the Java section and we will make sure to get this fixed.