I have a lineone address, (which became Tiscali). I could not download either with Outlook, Outlook Express or even from the TalkTalk web mail site.
All this happened after the transfer of the Tiscali mail server to the TalkTalk one. It seems this caused chaos. Some passwords were "lost" and needed to be reset, other accounts produced errors saying mail box full. Lots of Tiscali accounts were affected.
I tried e-mailing customer support few times, but they were no help. Finally, in desperation I e-mail the TalkTalk CEO, and he got someone to sort it out. All OK now.
Your friends problem in somewhat different in that she can access the TT main site. I suggest she tries creating an new connection in OE, checking all the settings. Obviously the account is active.