ubuntu hardy apt-get upgrade Hash Sum mismatch

today on one of my server box occurde a “Hash Sum mismatch”.
why suddenly ?

apt-get upgrade

Fetched 1B in 0s (4B/s)
W: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/hardy-security/multiverse/binary-amd64/Packages.bz2  Hash Sum mismatch

*Update:*
one day later, doing nothing this error message is gone. i suppose a problem on the used mirror.

symfony upgrade to 1.1.1 failed

As Nicolas Perriault published on symfony’s blog the bugfix version 1.1.1 was released-

I tried this upgrade procedure, but it failed:

pear upgrade symfony/symfony-1.1.1
downloading symfony-1.1.1.tgz ...
Starting to download symfony-1.1.1.tgz (2,131,490 bytes)
.................................................................................................................................................................................................................................................................................................................................................................done: 2,131,490 bytes

Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 82 bytes) in /usr/share/php/PEAR/Registry.php on line 1061

environment: Ubuntu
Linux 2.6.24-19-generic #1 SMP Fri Jul 11 21:01:46 UTC 2008 x86_64 GNU/Linux

*Update:*

fixed by setting memory_limit from default 32M to 128M in php.ini:
grep memory_limit /etc/php5/cli/php.ini
memory_limit = 128M ; Maximum amount of memory a script may consume (32MB)