FF3不能安装 allinone sidebar

Error: [Exception... "Component returned failure code: 0x80520015 (NS_ERROR_FILE_ACCESS_DENIED) [nsISafeOutputStream.finish]"  nsresult: "0x80520015 (NS_ERROR_FILE_ACCESS_DENIED)"  location: "JS frame :: file:///C:/Program%20Files/Mozilla%20Firefox/components/nsExtensionManager.js :: closeSafeFileOutputStream :: line 508"  data: no]
Source File: file:///C:/Program%20Files/Mozilla%20Firefox/components/nsExtensionManager.js
Line: 508

可是它标称支持ff3的啊。