Pendrives work quite slowly

[JMGM]

I have a big problem. Since I use Vista my pendrives work quite slowly when I
insert them in the USB ports. It takes several minutes to read only the root
and more if I try to see the contents of some folders. After this (if Windows
Explorer doesn't hang and suggest to close and run again) I have access to my
pendrives at a normal speed.

 

[JMGM]

I have a big problem. Since I use Vista my pendrives work quite slowly when I
insert them in the USB ports. It takes several minutes to read only the root
and more if I try to see the contents of some folders. After this (if Windows
Explorer doesn't hang and suggest to close and run again) I have access to my
pendrives at a normal speed.

I forgot to say that the problem keeps when I uninstall my antivirus and
restart the computer.