Hello there

I've just replied your support ticket, but I'll ask you again here in case if you're reading here more quickly:
Which package was it?
Are you connected via Wifi or Edge? I think Edge won't work too well with Installer, but I could be wrong (I'm a poor iPod Touch Owner).
I don't modify the source's XML, so when Installer throws an error, it usually has to do with source's server acting up, or the original source creator did something wrong with their source... But, if you can provide me with the package you're having problem with, I can definetly try and track down the problem for you manually.