If you’re running Ubuntu Netbook Edition (UNE) Lucid Lynx (10.04 LTS) you’ll have problems using OpenPGP/ GnuPG because the Maximus desktop daemon interferes with the pinentry window. For example:

1. When receiving an encrypted email gpg-agent launches the pinentry window requesting your OpenPGP passphrase.
2. The screen briefly flickers when the pinentry window is opened and immediately closes.
3. This behaviour is repeated three times before Evolution (for instance) reports an error: “public key decryption failed: bad passphrase“.

Fortunately, this is easily resolved:

1. Open Gnome Terminal and type gconf-editor.
2. Select apps->maximus.
3. Double-click exclude-class key.
4. Click Add and type ‘pinentry’ followed by OK.

I’ve tested this solution with Evolution and GPG, e.g. gpg –clearsign.

Bug #573195 in maximus refers.