我用的是win7系统 和 VMware7.0的虚拟机，插上USB时，在VM里不识别，连接时总是出现The VMWare USB Arbitrator returned error code 4.有时候出现的错误是The VMWare USB Arbitrator returned error code 9. 在网上的参考资料：http://hi.baidu.com/sdvch/item/f82ec2136eb6668388a95691对我来说没有用。最后看到一个解决方案：

1. After receiving "VMWare USB Arbitrator returned error code 4" in VM, I went to "Device Manager" on my HOST system (Not guest VM)

2. I observed whenever I try to connect USB device thru VM menu of VMWare workstation, a device named "VMWare USB Device" appears into my HOST's "Device Manager" with yellow mark.

3. I updated driver by pointing to "c:\Program Files (x86)\Common Files\VMWare\USB" folder.

4. Once the driver was updated on the HOST system, I went back to VMWare workstation and bingo! I  found that my XP VM had already detected the USB device.

Summary: In my case, problem was that my HOST system was not finding driver for "VMWare USB device", which appears when you try to connect USB device in VM.

Hope this helps!

所以，我想我的也可能是VM下的USB驱动的问题，然后去网上下了VM 的USB驱动，下载地址：

然后我打开设备管理器，插入U盘，在设备管理器的通用串行总线控制器那里能看到"USB 大容量存储器"这一条,当然此时的U盘是连在win7系统之下的，然后我在VM里面点那个USB的连接，此时就会弹出上面的那个错误，然后在设备管理器的其它设备栏里看到：USB2.0-CRW的一条项，然后我右键选择更新驱动，选择刚下载的那三个文件，装完之后在通用串行总线控制器那个条目里多出现了一个条目：VMwaer USB Device, 那个SB 大容量存储器 条目也还在，此时在VM虚拟机里面就能看到插入的U盘了。