**EDIT:** I can run the same program twice, simultaneously without any problem - how can I duplicate this with OpenMP or with some other method? This is the basic framework of the problem. //Defined elsewhere class SomeClass { public: void Function() { // Allocate some memory float *Data; Data = new float[1024]; // Declare a struct which will be used by functions defined in the DLL SomeStruct Obj; Obj = MemAllocFunctionInDLL(Obj); // Call it FunctionDefinedInDLL(Data,Obj); // Clean up MemDeallocFunctionInDLL(Obj); delete [] Data; } } void Bar() { #pragma omp parallel for for(int j = 0;j<10;++j) { SomeClass X; X.Function(); } } I've verified that when some memory is attempted to be deallocated through `MemDeallocFunctionInDLL()`, the `_CrtIsValidHeapPointer()` assertion fails. Is this because both threads are writing to the same memory? So to fix this, I thought I'd make `SomeClass` private (this is totally alien to me, so any help is appreciated). void Bar() { SomeClass X; #pragma omp parallel for default(shared) private(X) for(int j = 0;j<10;++j) { X.Function(); } } And *now* it fails when it tries to **allocate** memory in the beginning for `Data`. **Note:** I can make changes to the DLL if required **Note:** It runs perfectly without `#pragma omp parallel for` **EDIT:** Now `Bar` looks like this: void Bar() { int j #pragma omp parallel for default(none) private(j) for(j = 0;j<10;++j) { SomeClass X; X.Function(); } } Still no luck.
Maybe not related, but memory allocated with new [] should be deleted with delete [].