XAMPP - PORTABLE + PHP DOCUMENTOR

I'm glad using my new xampp portable, with the XAMPP-launcher. But I've been triyng to install PhpDocumentor to it, without success..

I've even tried to instal PhpDocumentor to my desktop xampp, only to copy the files. But had no success either...

The way I tried is:
>cd c:\xampp\php
c:\xampp\php>pear install PhpDocumentor

The answer is:
Notice: unserialize(): Error at offset 53 of 351 bytes in Config.php on line 100
3
Error: The default config file is not a valid config file or is corrupted.

I've tried to do from g:\xampp\php as well, but windows won't let me, but that's ok. If I could install at least to my desktop xampp, it would be nice. I would copy the files to my portable one..

Any clues? Thank's!

EDIT 1:
//-------------------------------------------------------------------------------
Now I found out how to access g:\xampp\php, but when I tried to install the PEAR package Net_UserAgent_Detect,
I used the command
g:\xampp\php>pear install Net_UserAgent_Detect
and I've got the similar answer

Notice: unserialize(): Error at offset 73 of 351 bytes in Config.php on line 100
3
Error: The default config file is not a valid config file or is corrupted.

Is that a problem with the poratble version??

EDIT 2:
//--------------------------------------------------------------------------------
the right command turned out to be
g:\xampp\php>pear install -f Net_UserAgent_Detect
-> the secret was to use the -f paramenter (-force installation)
-> havet't tried again the PhpDocumentor intallation. Let you know if I try