在eclipse里无法启动tomcat?

放假前还好好的.今天上午启动,报如下错误.
在网上搜了一下,提供的解决方案基本是说,
虽然xml文件声明是utf-8格式,可是实际存的时候却不是utf-8的.于是,建议在server.xml文件的最上面加上一行
<?xml version='1.0' encoding='utf-8'?>
我的server.xml文件本来的最上面这行也是这样.所以我就在root.xml文件的最上面也加了这行,也不管用.
严重: Error deploying configuration descriptor ROOT.xml
com.sun.org.apache.xerces.internal.impl.io.MalformedByteSequenceException: Invalid byte 2 of 2-byte UTF-8 sequence.
at com.sun.org.apache.xerces.internal.impl.io.UTF8Reader.invalidByte(UTF8Reader.java:674)
at com.sun.org.apache.xerces.internal.impl.io.UTF8Reader.read(UTF8Reader.java:362)
at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.load(XMLEntityScanner.java:1742)
at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.scanData(XMLEntityScanner.java:1242)
at com.sun.org.apache.xerces.internal.impl.XMLScanner.scanComment(XMLScanner.java:756)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanComment(XMLDocumentFragmentScannerImpl.java:1036)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:945)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:648)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:807)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1205)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522)
at org.apache.tomcat.util.digester.Digester.parse(Digester.java:1628)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:583)
at org.apache.catalina.startup.HostConfig.deployDescriptors(HostConfig.java:553)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:488)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1149)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:311)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:719)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
at org.apache.catalina.core.StandardService.start(StandardService.java:516)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
at org.apache.catalina.startup.Catalina.start(Catalina.java:578)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
2010-4-6 15:48:44 org.apache.coyote.http11.Http11AprProtocol start
信息: Starting Coyote HTTP/1.1 on http-80
2010-4-6 15:48:44 org.apache.coyote.ajp.AjpAprProtocol start
信息: Starting Coyote AJP/1.3 on ajp-8009
2010-4-6 15:48:44 org.apache.catalina.startup.Catalina start
信息: Server startup in 700 ms请各位大侠帮忙解决!谢谢!!!