Fixing sandbox execution issue

I faced the following issue while working with SharePoint 2010

"The sandboxed code execution request was refused because the Sandboxed Code Host Service was too busy to handle the request”

 Solution:

1) Open "Hosts" file from the following location:

    C:\Windows\System32\drivers\etc

2) Make this entry

    127.0.0.1     crl.microsoft.com

4) Restart the "SharePoint 2010 User Code Host" service on all these servers

3) IIS Reset

For other alternatives, please refer this blog.