Cannot complete the install because of a conflicting dependency.
  Software being installed: m2e connector for build-helper-maven-plugin 0.15.0.201109282249 (org.sonatype.m2e.buildhelper.feature.feature.group 0.15.0.201109282249)
  Software currently installed: m2e - Maven Integration for Eclipse 1.2.0.20120828-2132 (org.eclipse.m2e.feature.feature.group 1.2.0.20120828-2132)
  Only one of the following can be installed at once: 
    Maven Integration for Eclipse 1.0.0.20110607-2117 (org.eclipse.m2e.core 1.0.0.20110607-2117)
    Maven Integration for Eclipse 1.0.200.20111228-1245 (org.eclipse.m2e.core 1.0.200.20111228-1245)
    Maven Integration for Eclipse 1.2.0.20120828-2132 (org.eclipse.m2e.core 1.2.0.20120828-2132)
    Maven Integration for Eclipse 1.2.0.20120822-1446 (org.eclipse.m2e.core 1.2.0.20120822-1446)
    Maven Integration for Eclipse 1.1.0.20120320-1102 (org.eclipse.m2e.core 1.1.0.20120320-1102)
    Maven Integration for Eclipse 1.0.100.20110804-1717 (org.eclipse.m2e.core 1.0.100.20110804-1717)
  Cannot satisfy dependency:
    From: m2e - Maven Integration for Eclipse 1.2.0.20120828-2132 (org.eclipse.m2e.feature.feature.group 1.2.0.20120828-2132)
    To: org.eclipse.m2e.core [1.2.0.20120828-2132]
  Cannot satisfy dependency:
    From: m2e connector for build-helper-maven-plugin 0.15.0.201109282249 (org.sonatype.m2e.buildhelper 0.15.0.201109282249)
    To: bundle org.eclipse.m2e.core [1.1.0,1.2.0)
  Cannot satisfy dependency:
    From: m2e connector for build-helper-maven-plugin 0.15.0.201109282249 (org.sonatype.m2e.buildhelper.feature.feature.group 0.15.0.201109282249)
    To: org.sonatype.m2e.buildhelper [0.15.0.201109282249]
I had previously done some, um, "unorthodox" activity with this Eclipse installation directory, so I went back and made a fresh Indigo SR2 installation, tried again, and got the same result.  That doesn't mean that there still isn't something screwy about my environment, but at a minimum I think the "Next" button in the "Install" dialog being enabled but behaving like a no-op is a bug.  And in any case, if someone could decode the "conflicting dependency" error above and give me some suggestions, I'd appreciate it.