A problem about "scan items with comodo antivirus"

Hi,everyone:

 I'm a Chinese cavl user. My English is poor , so I hope you guys can understand what I say.

 Because I often need use the removable flash disk to copy some files , so I really need Linux system and a antivirus for it. I searched many of them, but some download address were closed , some not free , and almost of them become for severs. Now I found cavl, I think  it is great. I use it 2 weeks. Then I find some problems. I use Ubuntu 14.04 x64 and Linux version 3.13.0-30-generic.

1.when I update the kernel, the shield will turn red , so I must re-install Filesystem Filter Driver. so there are some ways to avoid this?
2. I find the speed of update is very slow…
3.when I use the “scan items with comodo antivirus”, I selected files, the scan window appeared but nothing happened just time increasing.

CAVL is great, I hope there will release new version soon!