now itÂ´s better, it was very high clock, by now i saw some industrial electronics using pics. But itÂ´s necessary to prevent high frequency for a specific application. If we can do it lower, better.
Not really. What is your high frequency and low frequency? I have used 20MHz and 40MHz with PIC 273, 245, 452, 4550... You said your circuit some times will not start. I think the problem may associated with the capacitors you used with your crystal. I use 18pF to 22pF and they are good. Also I used 56K and 1uF for the MCLR; you may want to have the PIC be stable with the voltage before MCLR goe HI to start your program.
So, please look at:
1. MCLR (resistor and capacitor)
2. Two cap used with the crystal
3. At program start up, use a little delay before setup port-pins
4. Pure DC for power supply. Check your supply (5 Volts or whatever voltage you use) to see if it is clean.
5. Put more than few decoupe caps around the circuit, specially the PIC and other IC (.1uF OK)
You also want to check your other component that may draw too much current when its active. It is good ideal to post your circuit and state detail your problems so other can help. What I said here is only a guess work, I don't know your circuit or what is the environment you are using; so I may not help you at all.
For the problem that when thePIC stops working when you touch the circuit. It may associate with the value of the capacitors connected to the crystal.
Want more help, post your circuit and state your problems in detail.