Debug desktop application for Windows and Mac - repost

I urgently need programmer who would be able to fix errors in simple desktop application. Application is working fine on Windows 7, but user noticed errors in Windows XP (e.g. Windows won't shut down if application is not closed). On Mac there are more error noticed by users, program is supposed to blink messages and pictures over any other program which is open, but it seems it is not working. If you have experience with developing desktop applications and think that you would be able to fix bugs in the software please apply. We will send you link to download the application. We need someone who is good with developing and testing both Windows and Mac application! We will need assistance occasionally and need someone who is available for long term cooperations! Also in future we will develop new applications so if you show us that you have good skills we will consider to hire you for new desktop applications! This should be easy task for experienced programmer.