Hi,
the new firmware is especially against your reported problems.
OK, if it will help you, it is no problem to replace the firmware by an older version. If you have an older image, you can use the tree firmware files (bootcode.bin , fixup.dat, start.elf) of it.
You can also use a firmware from the official RPI webpage.
It is also possible to revert to an older snapshot and than only upgrade all other packages.
Claus