Gustaf, I run Mplab 3.99.06 on win 98, no such problems. I suspect that one of your include files was in an unspecified(unknown) path, but you will not realy know without opening your *.err error file of same prefix as the *.asm you are compiling. regards, Graham Daniel. Electronic Product Enhancements. Gustaf Tham wrote: > > Thanks for replying. However, I tried MPLAB 39923, > but the problem remained. > After changing back to Win95, everything is normal again. > No more Win98 for me. > > Gustaf >