Comment 12 for bug 799378

This issue is certainly not fixed, please do not change the status unless you can find a patch that specifically addresses it.
It is a complicated issue inherent to the OpenERP module dependency system and the inheritance mechanism, and it will not be fixed by chance.
If you cannot reproduce it with the simple test case of installing the base_contact module after the crm module, it's only because the installation procedure is slightly different in 6.1, as Thu explained in comment #5. The issue will appear nevertheless as soon as the server is restarted, and as long as the base_contact module is loaded before the crm module ( you can see the loading order in the server log).

BTW the workaround is very simple: either force a dependency between the conflicting modules, e.g. make crm depend on base_contact, or even simpler, manually force an update of the module in which the error occurs (in this case crm), and it will permanently solve the issue.

PS: Independently of this bug, it seems many people believe base_contact to be an important and frequently needed module. This is mostly not correct, and base_contact is not needed at all to manage contacts. On a database without base_contact, the contacts are simply the partner addresses. The only case where base_contact is required is when the same contact needs to be associated with several parent companies. In most cases this is not needed, and for few odd cases where a contact belongs to multiple partners, duplicating it is fine. Avoiding to install base_contact will save you from a lot of trouble.