I have same problem here..mIRC works fine on my old computer,but I've bought new computer few days ago..When I run mIRC,nothing happens.He shows mirc.exe in task manager for a half of second,and then he just disappear..I have tried to reinstall my OS,but same again..I tried to turn off AV,firewall,and nothing..Here is my system conf...

Proccessor:AMD Phenom64 X3 8650 BOX
Motherboard:ASUS
Ram Memory:DDR2 4GB 800MHz
Grafic card:ASUS 3650 SIL/1GB
HDD:WD 500GB SATAII 8mb cache
OS: Windows XP SP2