weblogix ioException

[Sang Monani]

my application is running fine but after a while i get this exception , where as i could go to this jsp page before and it use to work.
restarting the server fixed the problem, but it re-appears after a while
can anyone tell me what is going wrong.
could it be memory problem or what
-----------------------------------------EXCEPTION---------------------------
location: package bean
if (_bean_message0 == null) _bean_message0 = new org.apache.struts.taglib.bean.MessageTag(
); //[ /contextmgt/listDomains.jsp; Line: 346]
^
Note: /apps/bea/wlserver6.1/config/WebCTDomain/applications/.wlnotdelete/wlap47589/WEB-INF/_tmp_war_webct/jsp_serv
let/_contextmgt/__listDomains.java uses or overrides a deprecated API.
Note: Recompile with -deprecation for details.
51 errors
>
java.io.IOException: Compiler failed executable.exec(java.lang.String[javac, -classpath, /apps/bea/wlserver6.1/con
fig/WebCTDomain/applications/.wlnotdelete/wlap47589/webct.war:/apps/bea/wlserver6.1/config/WebCTDomain/application
s/.wlnotdelete/wlap47589/WEB-INF/_tmp_war_webct/WEB-INF/lib/struts-validator29712.jar:/apps/bea/wlserver6.1/config
/WebCTDomain/applications/.wlnotdelete/wlap47589/WEB-INF/_tmp_war_webct/WEB-INF/lib/struts29713.jar:/apps/bea/wlse
rver6.1/config/WebCTDomain/applications/.wlnotdelete/wlap47589/WEB-INF/_tmp_war_webct/cls29639.jar:/apps/bea/wlser
ver6.1/config/WebCTDomain/applications/.wlnotdelete/wlap47589/WEB-INF/_tmp_war_webct:/apps/bea/wlserver6.1/config/
WebCTDomain/applications/.wlnotdelete/wlap47589/struts.jar:/apps/bea/wlserver6.1/config/WebCTDomain/applications/.
wlnotdelete/wlap47589/struts-validator.jar:/apps/bea/wlserver6.1/config/WebCTDomain/applications/.wlnotdelete/wlap
47589/serverclasses.jar:/apps/bea/wlserver6.1/