Dei uma olhada no log e vi que o erro era o seguinte:
2010-09-16 09:50:49,111 INFO [STDOUT] (http-0.0.0.0-8080-6) Acabou de salvar o arquivo..:C:\JavaAppDev5\jboss-5.1\server\default\tmp\5c4ol2y-kj6550-ge5majvt-1-ge5mbqot-b1\siscoweb.war\UploadArquivo/Upload_9050049.mdb
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) java.sql.SQLException: [Microsoft][Driver ODBC para Microsoft Access] Recurso do sistema excedido.
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at sun.jdbc.odbc.JdbcOdbc.createSQLException(JdbcOdbc.java:6957)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at sun.jdbc.odbc.JdbcOdbc.standardError(JdbcOdbc.java:7114)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at sun.jdbc.odbc.JdbcOdbc.SQLDriverConnect(JdbcOdbc.java:3073)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at sun.jdbc.odbc.JdbcOdbcConnection.initialize(JdbcOdbcConnection.java:323)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at sun.jdbc.odbc.JdbcOdbcDriver.connect(JdbcOdbcDriver.java:174)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at java.sql.DriverManager.getConnection(DriverManager.java:582)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at java.sql.DriverManager.getConnection(DriverManager.java:185)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at siscoweb.servlets.srvControlador.atualizaCambio(srvControlador.java:1607)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at siscoweb.servlets.srvControlador.atualizacao(srvControlador.java:1122)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at siscoweb.servlets.srvControlador.processRequest(srvControlador.java:872)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at siscoweb.servlets.srvControlador.doPost(srvControlador.java:86)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:829)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:598)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
2010-09-16 09:50:50,251 ERROR [STDERR] (http-0.0.0.0-8080-6) at java.lang.Thread.run(Thread.java:619)
Será que alguém pode ajudar? Obrigado!