10.04 -> 10.10 upgrade impossible

[Roberto Sbragia]

I've tried to upgrade my Ubuntu 64 bit 10.04 to 10.10 but the upgrade is impossible:

[Impossible to calculate the progress]*
An unresolvable problem occurred while calculating the upgrade:
E:Errore, pkgProblemResolver::[Resolve generated breaks. This could be caused by held packages.]*
 This can be caused by:
 * Upgrading to a pre-release version of Ubuntu
 * Running the current pre-release version of Ubuntu
 * Unofficial software packages not provided by Ubuntu
[If the cause is not one of these, please report the bug for the package "update-manager" in the report include the files in / var / log / dist-upgrade /.]*

* text in [ ] translated from italian using google translate