Do yo have any html code in your project, try the preview without the code for test and see if this is better.

If so then it's better to remove it and it it before uploading, it sometimes blocks in preview.

Try also to clear your internal cash of your pc and see if this helps.

I had this problem on my WIn7 x64 machine and I found I had to shut down the preview with the Task Manager - and then WX5 crashed.

My problem came down to the .NET Framework needing repair - I removed it and re-installed it using Microsoft's tool and .NET4 download. I also had to turn off and on the .NET 3.5 Framework. This done everything worked OK for me.

The repair method used was:

For Windows 7:

Repair the .NET Frameworks 3.5 and 4 first using following tool to remove .NET 4:

http://www.microsoft.com/en-gb/download/details.aspx?id=30135

Once done, go to Control Panel then choose Programs and Features and then click on Turn Windows features on or off. Clear the check box for Microsoft .NET Framework 3.5.1 and then click on OK. After Windows disables the feature you will need to go back to re-enable Microsoft .NET Framework 3.5.1.

Then reinstall .NET 4 after downloading it from:

http://www.microsoft.com/en-us/download/details.aspx?id=17718

Method for Windows 8:

Go to Control Panel > Programs and Features > Turn Windows features on or off
Clear the check box for Microsoft .NET Framework 3.5.1 and click on OK; do the same for Microsoft .NET Framework 4.5.
After Windows disables the feature you will need to go back to re-enable Microsoft .NET Framework 3.5.1 and 4.5 and then click ok.

Hope this fix works for you,

Regards,

Mark.