Android - Keep getting "Error retrieving information from server. [RH-01]" from the play store

This could be caused by flashing an incompatible GApps package. If that's not the case (and you are sure you have the correct/compatible GApps installed), try the following:

1. Open the "Google Play" app and press the home button to return
2. Go to Settings → Applications → Manage Applications
3. Select the "ALL" tab, Search for "Google Play Store" and press it to open.
4. Press "Clear cache"
5. Press "Force stop"
6. Return to Settings → Applications → Manage Applications
7. Press "Google Services Framework"
8. Press "Clear Data"
9. Press "Force Stop"
10. Start "Google Play Store" and it should give an error
11. Reboot. Once your device has restarted Google Play Store should work. Wait a minute or too if it doesn't.

This should help if a corrupt cache is the cause of your problems (a corrupt cache might lead to strange error messages, amongst others). If it doesn't help, you might try the same steps but include "Clear Data" for the playstore app.

Apparently some custom ROMs do not come with any Google services and to fix this you need to flash gapps using a program such as Clock Work Mod. This page has a link to download gapps.