Hi,  this same thing started happening to me today. I realized that it was after the first reboot I did after the new FontExplorer X Pro plugin was installed.

I was getting out of memory errors or Illustrator CS6 was crashing right after trying to open a file.

I disabled the plugin and am having no problems so in my case at least the issue seems to be with LinoType's plugin.

Also, for anyone who is having this issue from the FontExplorer X CS6 plugin please submit a trouble ticket to Linotype at http://www.fontexplorerx.com/support/  (if the link gets removed fromthe post just go to the font explorer website and click the support button in the upper right)

You're welcome. That's my same job. The only problem is that now we're stuck having to manually activate font's again . . . I'm not very happy with Linotype. Please make sure and submit a trouble ticket at Linotype so we can all light a fire under them to get this fixed.

When am I going to learn to not upgrade to the newest version of CS right away?

I am getting the same "...isn't enough memory" message when I try to open a file, but unfortunately, I don't have the fontexplorer plug-in installed.  Strangely, after I click OK to the message, Illustrator shows me a frozen progress bar dialog sitting at 100% (the process is complete) with the text "Transform" listed on the dialog.  I'm wondering if some Transform effect is corrupt (I do use a lot of those in my illustrations)?  Any suggestions?  I've got 8MB of RAM on my MacBook Pro, running 10.6.8 and I've shut down every application but Illustrator.  Still no dice.

Trashing preferences solved problem. Disabling Font Explorer plugin, repairing permissions and Onyx cleaning did not.