运行 Selenium Ruby Webdriver 脚本时遇到问题，如下所示：
Selenium 完成运行我的脚本后，浏览器关闭（这是预期的行为）。但是，紧接着，浏览器重新打开，什么也不做，然后关闭，不断地，浏览器重新打开然后关闭。在浏览器（FF16，或 IE9，或 Chrome）完全关闭之前，这件事重复了大约 4 次。
每次打开和关闭浏览器时都会显示以下日志消息。请注意，我正在使用 @driver.quit 来关闭浏览器。请帮助指导我需要做些什么来克服这种不便的情况。非常感谢。
*** LOG addons.xpi: shutdown
E*** LOG addons.manager: Application has been upgraded
*** LOG addons.xpi: startup
*** LOG addons.xpi: Skipping unavailable install location app-system-local
*** LOG addons.xpi: Skipping unavailable install location app-system-share
*** LOG addons.xpi: checkForChanges
*** LOG addons.xpi-utils: Opening database
*** LOG addons.xpi-utils: Creating database schema
*** LOG addons.xpi: New add-on fxdriver@googlecode.com installed in app-prof
*** Blocklist::_loadBlocklistFromFile: blocklist is disabled
*** LOG addons.xpi: New add-on {82AF8DCA-6DE9-405D-BD5E-43525BDAD38A} instal
in app-global
*** LOG addons.xpi: New add-on {972ce4c6-7e08-4474-a285-3208198ce6fd} instal
in app-global
*** LOG addons.xpi: Updating database with changes to installed add-ons
*** LOG addons.xpi-utils: Updating add-on states
*** LOG addons.xpi-utils: Writing add-ons list
*** LOG addons.xpi: shutdown
*** LOG addons.xpi-utils: shutdown
*** LOG addons.xpi-utils: Database closed
*** LOG addons.xpi: startup
*** LOG addons.xpi: Skipping unavailable install location app-system-local
*** LOG addons.xpi: Skipping unavailable install location app-system-share
*** LOG addons.xpi: checkForChanges
*** LOG addons.xpi: No changes found
*** Blocklist::_loadBlocklistFromFile: blocklist is disabled
!!! error running onStopped callback: TypeError: callback is not a function
*** LOG addons.xpi: shutdown
E*** LOG addons.manager: Application has been upgraded
*** LOG addons.xpi: startup
*** LOG addons.xpi: Skipping unavailable install location app-system-local
*** LOG addons.xpi: Skipping unavailable install location app-system-share
*** LOG addons.xpi: checkForChanges
*** LOG addons.xpi-utils: Opening database
*** LOG addons.xpi-utils: Creating database schema
*** LOG addons.xpi: New add-on fxdriver@googlecode.com installed in app-prof
*** Blocklist::_loadBlocklistFromFile: blocklist is disabled
*** LOG addons.xpi: New add-on {82AF8DCA-6DE9-405D-BD5E-43525BDAD38A} instal
in app-global
*** LOG addons.xpi: New add-on {972ce4c6-7e08-4474-a285-3208198ce6fd} instal
in app-global
*** LOG addons.xpi: Updating database with changes to installed add-ons
*** LOG addons.xpi-utils: Updating add-on states
*** LOG addons.xpi-utils: Writing add-ons list
*** LOG addons.xpi: shutdown
*** LOG addons.xpi-utils: shutdown
*** LOG addons.xpi-utils: Database closed
*** LOG addons.xpi: startup
*** LOG addons.xpi: Skipping unavailable install location app-system-local
*** LOG addons.xpi: Skipping unavailable install location app-system-share
*** LOG addons.xpi: checkForChanges
*** LOG addons.xpi: No changes found
*** Blocklist::_loadBlocklistFromFile: blocklist is disabled
!!! error running onStopped callback: TypeError: callback is not a function
*** LOG addons.xpi: shutdown
E*** LOG addons.manager: Application has been upgraded
*** LOG addons.xpi: startup
*** LOG addons.xpi: Skipping unavailable install location app-system-local
*** LOG addons.xpi: Skipping unavailable install location app-system-share
*** LOG addons.xpi: checkForChanges
*** LOG addons.xpi-utils: Opening database
*** LOG addons.xpi-utils: Creating database schema
*** LOG addons.xpi: New add-on fxdriver@googlecode.com installed in app-prof
*** Blocklist::_loadBlocklistFromFile: blocklist is disabled
*** LOG addons.xpi: New add-on {82AF8DCA-6DE9-405D-BD5E-43525BDAD38A} instal
in app-global
*** LOG addons.xpi: New add-on {972ce4c6-7e08-4474-a285-3208198ce6fd} instal
in app-global
*** LOG addons.xpi: Updating database with changes to installed add-ons
*** LOG addons.xpi-utils: Updating add-on states
*** LOG addons.xpi-utils: Writing add-ons list
*** LOG addons.xpi: shutdown
*** LOG addons.xpi-utils: shutdown
*** LOG addons.xpi-utils: Database closed
*** LOG addons.xpi: startup
*** LOG addons.xpi: Skipping unavailable install location app-system-local
*** LOG addons.xpi: Skipping unavailable install location app-system-share
*** LOG addons.xpi: checkForChanges
*** LOG addons.xpi: No changes found
*** Blocklist::_loadBlocklistFromFile: blocklist is disabled
!!! error running onStopped callback: TypeError: callback is not a function