software update not working

[Thomas Blasejewicz]

Good morning
Now I have a problem with the "software updater".
Made new, clean installations of "Tuxtrans" (xubuntu 14.01 + a whole
bunch of translation related software tools) on two different computers.
(replacing in the process also the Mint installations, because I could
not resolve the keyboard trouble I have been asking about the other day)

One is working somehow after the second installation.
The other (Dell inspiron 1545) shows up from the beginning (tried three
times) with a red warning sign
in the notification area telling me "A problem occurred when checking
for the updates".
Attempts to check for updates or starting the Synaptic Package Manager fail.

Is there a way to fix this?
Thank you.
Thomas