Arduino Pro Mini 5v/16Mhz ; must press reset before code will run

Hi everyone; I've done some research on this and haven't been able to find an answer. What I'm running across is, I can load my code to my pro mini just fine, but once I power it up, the code doesn't seem to load ; I have to press the reset button on the mini, then the code loads just fine. I found a thread where the issue was being had with an older Uno, but it was after a code upload, not power up. I went ahead and added a diode between RST and VCC with the cathode facing VCC, as the thread suggested, just to try it. Same issue. Any ideas?

You can close/ignore this thread, I found the problem. The arduino was NOT the problem. I decided to connect it to my serial port to see if it was sending the data request it was supposed to, and it was. After going back over my PCB, I found I'd missed connecting the address bits of my I2C port expander to ground. Doing that fixed my issue.

Wiring error, will get you every time!

just a tough, is this not caused by the defect on autoreset capacitor ? 100nf one ? because I have a similar problem before with my mega 2560 compatible board and try a couple of solution by upgrading / reflashing the DFU (atmega8u2), re-burn the bootloader and etc ... but still have no luck. Until some moment I decided to change the autoreset capacitor with the new one. and after this the board is back normal.

see here for more detail http://www.arvydas.co.uk/wp-content/uploads/2010/01/arduino-reset-mod.jpg

I've never seen a 0.1uF cap go bad, but I suppose anything is possible.

CrossRoads: I've never seen a 0.1uF cap go bad, but I suppose anything is possible.

there is no harm to try :)