bad signatures preventing install
 

whenever I try to install any package of software in mandrake 10, it says it has a bad signatures [missing signatures:couldn't open file]. I ignore this but it still fails to install - says 'There was a problem with the installation, ...retrieval failed, curl failed, exited with 9 or signal 0.
Please help I have no idea what these mean or what to do. Using urpmi just seems to manage to uninstal packages I already have...

if you are trying to install from a urpmi source, you may need to upgrade your urpmi sources.

Try using different servers.

sorry - newbie here! How do I do either of those thinngs please?

go here for a tutorial