我用的是win7系統 和 VMware7.0的虛擬機，插上USB時，在VM裏不識別，連接時總是出現The VMWare USB Arbitrator returned error code 4.有時候出現的錯誤是The VMWare USB Arbitrator returned error code 9. 在網上的參考資料：http://hi.baidu.com/sdvch/item/f82ec2136eb6668388a95691對我來說沒有用。最後看到一個解決方案：
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驅動的問題，然後去網上下了VM 的USB驅動，下載地址：
然後我打開設備管理器，插入U盤，在設備管理器的通用串行總線控制器那裏能看到"USB 大容量存儲器"這一條,當然此時的U盤是連在win7系統之下的，然後我在VM裏面點那個USB的連接，此時就會彈出上面的那個錯誤，然後在設備管理器的其它設備欄裏看到：USB2.0-CRW的一條項，然後我右鍵選擇更新驅動，選擇剛下載的那三個文件，裝完之後在通用串行總線控制器那個條目裏多出現了一個條目：VMwaer USB Device, 那個SB 大容量存儲器 條目也還在，此時在VM虛擬機裏面就能看到插入的U盤了。