Session data is showing corruption or strange character set

[eluser]gentleJuggernaut[/eluser]
The output of my codeigniter site has started to show strange characters on standard output (I have simplified the output to <h1>testing</h1>). The issue only happens after I reference the session (destroy, create or try to add data to). Then any output going to the browser shows as strange characters. Could be a different character set. The oddest thing about this is that it only happens when connected through the ATT network. Literally. The other odd thing is that other sites I know that use sessions are not having this problem (i.e. a site that uses the framework concrete5 can log in with no corruption or strange response). Any ideas or suggestions for something to try would be appreciated.

NSM

[eluser]gentleJuggernaut[/eluser]
after a little trial and error, it seems that the issue was with the CI Sessions and the ATT network (not sure how this is possible). When I replaced the Session.php file with one found here (http://ellislab.com/forums/viewthread/93200/) using native php sessions, the issue was resolved. Thanks to Adam Griffiths and yaron (added the flashdata code) for this Native solution. You guys rock!