Just try these for once and see:
1. "aspnet_regiis -u"
2. "aspnet_regiis -i"
3. iisreset
If above does not work then try:
1. "aspnet_regiis -u"
2. Uninstall IIS
3. Reboot
4. Reinstall IIS
5. "aspnet_regiis -i"
6. Iisreset
Just a suggestion - nothing concrete, they work at times!