Internal build error occurs intermittently

Steps to reproduce:
1.import the attached project
2.Export release build(unable to export release build(FB-27685)) .
3.Try to play around with compiler settings.

Actual Results:Internal build error occurs

Expected Results:No error should occur

PFA the log entry:

!ENTRY com.adobe.flexbuilder.project 4 43 2010-10-21 13:35:34.556
!MESSAGE Uncaught exception in compiler
!STACK 0
java.lang.NullPointerException
at flex2.tools.oem.Application.loadCachedSources(Application.java:737)
at flex2.tools.oem.Application.recompile(Application.java:1232)
at flex2.tools.oem.Application.compile(Application.java:878)
at flex2.tools.flexbuilder.BuilderApplication.compile(BuilderApplication.java:359)
at com.adobe.flexbuilder.multisdk.compiler.internal.ASApplicationBuilder$MyBuilder.mybuild(ASApplicationBuilder.java:300)
at com.adobe.flexbuilder.multisdk.compiler.internal.ASApplicationBuilder.build(ASApplicationBuilder.java:142)
at com.adobe.flexbuilder.multisdk.compiler.internal.ASBuilder.build(ASBuilder.java:191)
at com.adobe.flexbuilder.multisdk.compiler.internal.ASItemBuilder.build(ASItemBuilder.java:78)
at com.adobe.flexbuilder.project.compiler.internal.FlexProjectBuilder.buildItem(FlexProjectBuilder.java:508)
at com.adobe.flexbuilder.project.compiler.internal.FlexProjectBuilder.build(FlexProjectBuilder.java:327)
at com.adobe.flexbuilder.project.compiler.internal.FlexIncrementalBuilder.build(FlexIncrementalBuilder.java:187)
Workaround (if any):