I have got the same issue.
Parse error: syntax error, unexpected T_FUNCTION in /www/blog/wp-content/plugins/category-posts-in-custom-menu/category-posts-in-custom-menu.php on line 125
I tried removing lines 123-127, which I assume are only comments, but still no change. Also tried clean install through the wordpress environment - didn't work - and finally I tried another clean installation by downloading the plugin to my client and then uploading to server via FTP - didn't work either. In my situation it might be clashing with changes I made on the functions.php
I hope one with greater php knowledge can debug this.
After all this experimentation wordpress deactivated the plugin automatically and upon manual activation it generates this:
Plugin could not be activated because it triggered a fatal error.
followed by the parse error.
Theme: Descartes 1.2 (modified)