After 3.5.1. upgrade insert media impossible

I get a “not found” error when trying to add a pic and save a post.
Without media, no problem.
Uploading is ok, then insert (125k) media ok, then save NOT.

Tried everything, even a totally new fresh install in a subdirectory with no plugins and twenty twelve standard theme.
So it has to do with 3.5.1 version and server combination, right?

Server:
Operating System : Linux?(64?Bit)
Server : Apache
Memory usage : 32.21 MByte
MYSQL Version : 5.1.66-cll
SQL Mode : Not set
PHP Version : 5.2.17
PHP Safe Mode : Off
PHP Allow URL fopen : On
PHP Memory Limit : 64
PHP Max Upload Size : 2M
PHP Max Post Size : 8M
PCRE Backtracking Limit : 500000
PHP Max Script Execute Time : 30s
PHP Exif support : Yes ( V1.4 )
PHP IPTC support : Yes
PHP XML support : Yes
Graphic Library:
GD Version : bundled (2.0.34 compatible)
FreeType Support : Yes
FreeType Linkage : with freetype
T1Lib Support : No
GIF Read Support : Yes
GIF Create Support : Yes
JPG Support : Yes
PNG Support : Yes
WBMP Support : Yes
XPM Support : Yes
XBM Support : Yes
JIS-mapped Japanese Font Support : No

Thanks in advance!