Paulo: Your problem (and apparently some of your acquaintances) is as you describe. If you read all the posts in this thread, you will see that there are multiple manifestations of THE problem, which is the failure of Time Machine to work as it historically (😉) has.
My problem is multiple: 1) that I have almost no access to the Time Machine drive - when I attempt to open it on my desktop I get an error message, 2) that I cannot enter Time Machine and select any item listed under Favorites and then Restore it. OTOH, I can enter Time Machine, select my computer under Devices, navigate to my Home, and Restore any item, at least those I've tried to restore. AND (vigorous knocking on wood can be heard now) both my Mac Pro and my MacBook Pro Time Machines are continuing to create backups as expected.
My machine is a MacBook Pro (17-inch, Late 2011), 2.5 GHz Intel Core i7, 8 GB 1600 MHz DDR3 running 10.10.1. Its Time Machine, connected via Airport, resides on the disk drive on a 2TB Airport Time Capsule 802.11AC, Part No. FE177LL/A, Model No. A1470.
My other machine is a Mac Pro (Early 2009), 2.66 GHz Quad-Core Intel Xeon, 8 GB 1066 MHz DDR3 ECC running 10.10.1. Its Time Machine, connected via USB 3.0, resides on a new 4-Bay Drobo w/ 4x4TB drives.