Problem with SE Bootloader Tool! - Sony Ericsson Xperia Mini, Mini Pro, Xperia Pro, A

Okay so i just re-locked my bootloader due to some problems and now wish to unlock it again. I ran into a problem a few days back with this tool :- http://forum.xda-developers.com/showthread.php?t=1560613
(NOTE- Earlier, I unlocked my bootloader with this tool only)
So what happened was that my windows 7 crashed and i thought of upgrading to windows 8. Since then, i've been getting this error (attached please see) With windows 7 this tool worked without any trouble. I also flashed lots of kernels with this tool!
I need to unlock my bootloader with method only as this is easy not not time consuming at all! Please help me!
I'll be grateful
-Ishan
PS:- Rest of the written stuff under 'DETAILS'
See the end of this message for details on invoking
just-in-time (JIT) debugging instead of this dialog box.
************** Exception Text **************
System.NullReferenceException: Object reference not set to an instance of an object.
at .(Object , EventArgs )
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ButtonBase.WndProc(Message& m)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
************** Loaded Assemblies **************
mscorlib
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.6387 (Win8RTM.050727-6300)
CodeBase: file:///C:/Windows/Microsoft.NET/Framework/v2.0.50727/mscorlib.dll
----------------------------------------
SE Bootloader_Unlocking_Relocking
Assembly Version: 1.5.0.0
Win32 Version: 1.5.0.0
CodeBase: file:///C:/IB/Android/Xperia/ROOT/SE%20bootloader/SE%20Bootloader_Unlocking_Relocking.exe
----------------------------------------
System.Windows.Forms
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.6387 (Win8RTM.050727-6300)
CodeBase: file:///C:/Windows/assembly/GAC_MSIL/System.Windows.Forms/2.0.0.0__b77a5c561934e089/System.Windows.Forms.dll
----------------------------------------
System
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.6387 (Win8RTM.050727-6300)
CodeBase: file:///C:/Windows/assembly/GAC_MSIL/System/2.0.0.0__b77a5c561934e089/System.dll
----------------------------------------
System.Drawing
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.6387 (Win8RTM.050727-6300)
CodeBase: file:///C:/Windows/assembly/GAC_MSIL/System.Drawing/2.0.0.0__b03f5f7f11d50a3a/System.Drawing.dll
----------------------------------------
HtmlAgilityPack
Assembly Version: 1.4.0.0
Win32 Version: 1.4.0.0
CodeBase: file:///C:/IB/Android/Xperia/ROOT/SE%20bootloader/HtmlAgilityPack.DLL
----------------------------------------
System.Xml
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.6387 (Win8RTM.050727-6300)
CodeBase: file:///C:/Windows/assembly/GAC_MSIL/System.Xml/2.0.0.0__b77a5c561934e089/System.Xml.dll
----------------------------------------
************** JIT Debugging **************
To enable just-in-time (JIT) debugging, the .config file for this
application or computer (machine.config) must have the
jitDebugging value set in the system.windows.forms section.
The application must also be compiled with debugging
enabled.
For example:
<configuration>
<system.windows.forms jitDebugging="true" />
</configuration>
When JIT debugging is enabled, any unhandled exception
will be sent to the JIT debugger registered on the computer
rather than be handled by this dialog box.