The circuit is just lousy. 56k ohms with 12V across it will draw about 214 microamps. If you have a particularly good 2N3906, it may have a gain (HFE) of 300, creating a collector current of 64 mA. This is a power dissipation of 77 milliwatts which is above the transistor's rating. As the transistor gets hot, the gain and leakage increase and destroy everything. 1K between the 2N3906 collector and 2N3904 base might allow the circuit to work without blowing up. No promises, though.