Memory issues with WP2.8?

I upgraded both my blogs, and someone else’s, from 2.7.1 to 2.8 this week, and have run into problems that I think may be memory issues.

1) The dashboard does not always display properly. Not all of the sections show, and a look at the HTML source shows the page hasn’t finished loading. If I disable plugins, it improves (in that more of the page works), but even disabling them all leaves the page incomplete.

2) Previously, any images I wanted to upload (and auto-thumbnail) had to be under 1000 pixels wide/high or I’d get a HTTP error or occasionally a 500 Server Error. I was told this was due to memory. It hasn’t been a problem, I just make sure images are under 1000 pixels. Now, however, they have to be under 600 or I get the same fault.

In the php.ini file, I have memory_limit = 64M. I’ve done a “clean” reinstall, and gone through all the troubleshooting steps suggested.

Am I missing something?