When I was doing unix programming in C (producer consumer pblm ). I found a strange thing that if 'printf' was used along with 'sleep' then the 'printf' statement wont execute...?

Can anybody tell me what is the problem....or
Do these to have any connection with each other..?

You can very well use printf along with sleep. An example of this usage is given below:

if ((fp=fopen(argv[1], "r+"))==NULL)
{
printf("Error: In reading File!");
sleep(1);
exit(1);
}

The above will print the error as
Error: In reading File!
and wait or delay for 1 second and then exit from the program.

Let me know how you have used so that I can help you more on this.