使用"help" -> "Check for Updates", 选择所有eclipse插件，升级。
升级完重启时，发生错误，IDE启动失败，报出如下错误：
org.osgi.framework.BundleException: Exception in org.eclipse.osgi.framework.internal.core.SystemBundleActivator.start() of bundle org.eclipse.osgi.
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:806)
Caused by: java.lang.IllegalStateException: The System Bundle could not be resolved: Another singleton version selected: org.eclipse.osgi_3.6.2.R36x_v20110210
at org.eclipse.osgi.internal.baseadaptor.BaseStorage.checkSystemState(BaseStorage.java:752)
Root exception:
java.lang.IllegalStateException: The System Bundle could not be resolved: Another singleton version selected: org.eclipse.osgi_3.6.2.R36x_v20110210
at org.eclipse.osgi.internal.baseadaptor.BaseStorage.checkSystemState(BaseStorage.java:752)
解决办法：
修改文件 "ECLIPSE_HOME\configuration\config.ini"
把
osgi.bundles=reference\:file\:org.eclipse.osgi_3.6.2.R36x_v20110210.jar@4,reference\:file\:org.eclipse.equinox.simpleconfigurator_1.0.200.v20100503.jar@1\:start
改为
osgi.bundles=reference\:file\:org.eclipse.equinox.simpleconfigurator_1.0.200.v20100503.jar@1\:start
PS：
完整配置文件如下：
#This configuration file was written by: org.eclipse.equinox.internal.frameworkadmin.equinox.EquinoxFwConfigFileParser
#Wed Mar 09 13:22:22 CST 2011
org.eclipse.update.reconcile=false
eclipse.p2.profile=epp.package.jee
osgi.instance.area.default=@user.home/workspace
osgi.framework=file\:plugins/org.eclipse.osgi_3.6.2.R36x_v20110210.jar
equinox.use.ds=true
eclipse.buildId=M20110210-1200
osgi.bundles=reference\:file\:org.eclipse.equinox.simpleconfigurator_1.0.200.v20100503.jar@1\:start
org.eclipse.equinox.simpleconfigurator.configUrl=file\:org.eclipse.equinox.simpleconfigurator/bundles.info
eclipse.product=org.eclipse.platform.ide
osgi.splashPath=platform\:/base/plugins/org.eclipse.platform
osgi.framework.extensions=
eclipse.application=org.eclipse.ui.ide.workbench
eclipse.p2.data.area=@config.dir/../p2/
osgi.bundles.defaultStartLevel=4
http://atealxt.appspot.com/article/20110309/eclipse_cannot_startup_when_update_to_helios_SR2.html