Weird error using PThread

[dinwal]

I have a project that I am working on. This is basically an extension of that. There is this weird error (Seg fault) when I run this code. What makes this error weird is that I print the value stored in the pointer and in the next line I pass that in a function at the curly braces where the function starts it throws an error saying "Cannot access memory location". GDB shows that a new thread was being created, I believe that thread invalidated the memory but the question is why. I have no clue. Appreciate your help. It's lots of files there so you can check it out using following command if you have svn installed:
svn checkout http://logic-simulator.googlecode.com/svn/trunk/ logic-simulator-read-only

The error is when we call InsertItems function. Thanks for looking.

[dkalita]

when u create a new thread it usually cannot access the memory allotted to other process including its parent. U need to use shared memory or other IPC for communication. I may not be correct totally but this is an IPC issue. Read on how to communicate between diferent processes.

[dinwal]

Thanks for your response. However, I am not creating a PThread here. It is getting created automatically. The error is way before I create it.
I print something like this:
fprintf(stderr, "inserting i =%d r = %d address=%p value=%d \n",i,r, &(InitMessages[i*r]),(&(InitMessages[i*r]))->item);

And it prints the values properly that means Initmessages is a valid pointer and accessible.
Now I call a function like this:
InsertItems(&(InitMessages[i*r]),r);
Basically, Initmessgaes has multiple of r items. Every time I call InsertItems I pass address of first item in the chunk of next r items. This function throws error that memory can not be accessed. I do not understand what is wrong as I can print the value and then send it. How could this be invalidated?
You can see the entire code by running above svn command to check out the project. Thanks.