Hi. Recently I've switched to php 5.5 with apcu extension and started to get weird fatal errors. After some investigations I found out that some of my User Cache Entries became broken.
At start I see this cached var

Array(    [strategy] => nested    [activate_locking] =>     [locking_timeout] =>3    [left] => lft    [level] => lvl    [right] => rgt    [root] => root    [parent] => parent    [useObjectClass] =>AsPages\Entity\Page)

And after several hours it becomes to

Array(    [└ьTоerro] => nested    [░8`о�9`о] =>     [=E■i�╕:`ом:`] =>3    [ф<`о] => lft    [uYо(] => lvl    [Remov] => rgt    [�] => root    [└╢N║�] => parent    [,|\о╠{\о<ю] =>AsPages\Entity\Page)

There were no such problems with php 5.4 and apc extension
The similar problem is described herehttp://stackoverflow.com/questions/18309583/doctrine-extension-bug-with-apcu-orm-treelistener-does-not-support-tree-type

I am using latest version of php 5.5.3 and dev version of apcu.
I face the problem both in Debian 7 and Ubuntu 12