Program crashes when releases UIImage after genera

Right now, I have followed this tutorial:

http://iphonedevelopment.blogspot.com/2009/05/opengl-es-from-ground-up-part-6_25.html

It does not work if I tried to release UIImage: I will get a 'EXC_BAD_ACCESS'. Now, I made the UIImage to be instance variables and retain them. I do not make it autorelease. But the problem is sometimes I want to delete my texture. I need to release those UIImage or else I will have a leak. (The Performance Tool Leaks report that UIImage causes leaks) But if I release UIImage, I will get EXC_BAD_ACCESS. And I am not even drawing them or accessing them anywhere at all. The program just crashes right at where it got release:

#0  0x30011940 in objc_msgSend ()
#1  0x302395f4 in CFGetTypeID ()
#2  0x308f480c in -[UIImage(UIImageDeprecated) imageRef] ()
#3  0x308f4ae0 in SharedIdentifierForImage ()
#4  0x308f4a30 in _UISharedImageDealloc ()
#5  0x308f4964 in -[UIImage dealloc] ()
#6  0x30236b78 in -[NSObject release] ()
#7  0x0000a374 in -[Texture dealloc] (self=0x184b30, _cmd=0x300f7fd0) at /Users/akaraphan/Desktop/Competition/TrapRoom/Classes/Texture.m:329
#8  0x30236b78 in -[NSObject release] ()
#9  0x30235f24 in CFRelease ()
#10 0x302043bc in __CFTypeCollectionRelease ()
#11 0x30205dac in __CFArrayReleaseValues ()
#12 0x30205c18 in __CFArrayDeallocate ()
#13 0x30236020 in _CFRelease ()
#14 0x30235efe in CFRelease ()
#15 0x3054836a in -[NSCFArray release] ()
#16 0x00011658 in -[GameSprite dealloc] (self=0x1838d0, _cmd=0x300f7fd0) at /Users/akaraphan/Desktop/Competition/TrapRoom/Classes/GameSprite.m:40
...
...

Line 329 in Texture.m is where I release my UIImage.

My code is a little different from the tutorial but it should be working very similarly:

- (id) initFromImage: (NSString*)imageFile{

    if (self = [super init]){

        path = [[NSBundle mainBundle] pathForResource:imageFile ofType:@"png"];
        texData = [[NSData alloc] initWithContentsOfFile:path];
        img = [[UIImage alloc] initWithData:texData];

        CGImageRef image = img.CGImage;

        width = CGImageGetWidth(image);
        height = CGImageGetHeight(image);

        if (image){
            int tempWidth = (int)width, tempHeight = (int)height;

            if ((tempWidth & (tempWidth - 1)) != 0 ){
                NSLog(@"CAUTION! width is not power of 2. width == %d", tempWidth);
            }else if ((tempHeight & (tempHeight - 1)) != 0 ){
                NSLog(@"CAUTION! height is not power of 2. height == %d", tempHeight);
            }else{
                GLubyte *spriteData = (GLubyte*) calloc(width * 4, height * 4);

                CGContextRef spriteContext = CGBitmapContextCreate(spriteData, width, height, 8, width*4, CGImageGetColorSpace(image), kCGImageAlphaPremultipliedLast);

                CGContextDrawImage(spriteContext, CGRectMake(0.0, 0.0, width, height), image);

                CGContextRelease(spriteContext);

                glGenTextures(1, &GLtexture);

                glBindTexture(GL_TEXTURE_2D, GLtexture);

                glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, spriteData);

                free(spriteData);

                CGImageRelease(image);

                NSLog(@"Texture %d", GLtexture);

            }

        }else NSLog(@"ERROR: Image not loaded...");

        return self;
    }
    return nil;
}

If you can see what is wrong, please guide me. Thank you.

Somehow removing