Guest account incompatibility issue Mac OS X Snow leopard 10.6
Mac OS X snow leopard contains numerous advanced features and settings for improved performance. As these are enhanced they might not comply with the settings of lower versions leading to incompatible issues in number of cases. One such example is that of guest account incompatibility issue.
On upgrading from leopard to snow leopard 10.6, bug existing in snow leopard could affect the system functionality, particularly if up gradation is done with guest account enabled. Though the bug itself does not cause any problem, instead it deletes other user account after guest account is used. Further resulting into loss of valuable data for accessing which user account is needed. Backup is utmost requirement to make up for data loss; if not Mac recovery program may be used.
There exists issue in handling guest account in Mac OS X snow leopard, when guest account enabled leopard is upgraded. Logging in and out from guest account and then once again logging to another user account significant data is found to be missing from the system.
Account configuration issues leading to incompatibility totally prevents access to the account. Moreover disabling or resetting guest account resets other account as well, causing loss of valuable data. Macintosh recovery is essentially required for resolving incompatibility issue and retrieving lost data.
However, in certain cases in which guest account was enabled after upgrading incompatible or other as such issues did not take place. This thereby accounts as a way to prevent problematic issues by disabling and later recreating the guest account. This way the account will have setting required by snow leopard in spite of having that of leopard. Or it can just be kept disabled if not required.
Non availability of backup is further meant to make situation complex. As soon as possible the data should be restored by scanning and locating data files, with mac recovery tool. It is an easy to do task much because of the GUI interface application is provided with.
Apart from that settings should always be checked prior to upgrading to know about incompatibility in order to avoid them and thus data loss or other errors taking place.

