Multiple Threads in C#

I am working on a class library that uses methods to create new threads that fire events when they are completed. Here's how it works.
1. Application calls method ResizeImageAsync(inputFile, outputFile, width, height);
2. The ResizeImageAsync() creates a new thread that runs in low priority with the IsBackground property = true.
3. The thread resizes the image and writes it to a folder based on the outputFile parameter.
3. The thread calls an event called OnResize(outputFile). The outputFile parameter is the value of the ResizeImageAsync() outputFile parameter.

The problem I am having is the ResizeImageAsync() method will be called multiple times at once. When I call it more than 30 times the computer hangs. I think it's because I am creating too many threads at once.
I haven't done very much multi-threading yet for an application so I'm not sure of which System.Threading class I should use to pool the threads so they are managed properly. I could just be disposing of the threads improperly as well.

I've attached some of the code in the application.

public event ResizeCompletedDelegate OnResize;
 
        public void ResizeImageMaxAsync(string imagePath, string outputPath, int maxWidth, int maxHeight)
        {
            Thread thread = new Thread(delegate()
                                           {
                                               this.ResizeImageMax(imagePath, outputPath, maxWidth, maxHeight);
 
                                               // Fire the completed event
                                               this.InvokeOnResize(outputPath);
                                           });
            thread.Priority = ThreadPriority.Lowest;
            thread.IsBackground = true;
            thread.Start();
        }
 
        private void InvokeOnResize(string filePath)
        {
            ResizeCompletedDelegate resizeDelegate = this.OnResize;
            if (resizeDelegate != null)
            {
                resizeDelegate(filePath);
            }
        }
 
 
// Application Usage Section.
 
// This is the event that will fire. It just writes out the path to the location of the resized image.
editor.OnResize += delegate(string outputFile)
        {
            Console.WriteLine("File: {0} Completed Resize", outputFile);
        };
 
// This is just an example of looping through multiple instances of the ResizeImageAbsoluteAsync method. It returns immediatelly after the thread is created and not when the thread has finished.
for (int i = 0; i < 60; i++)
{
    editor.ResizeImageAbsoluteAsync(imagePath, String.Format(outputPath, Guid.NewGuid().ToString()), 250, 250);
}

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