Cannot send files larger than 10K??

[Andras Simonyi <simka@ludens.elte.hu>]

Hello,
I have a very strange problem on a rather screwd up, potato-woody
hybrid: I can't send longer e-mails (ie. with attachments), and I
even cannot upload longer files to FTP servers. In both cases, the
symptomes are the same: the system starts sending and for a short
time my modem lights are indicating the sending of data, but after a
few seconds it stops and nothing happens, till I kill the process.
Short letters and files are OK -- I'm sending this email from home. 
Any ideas???

TIA: Andras