Locked out of Hudson after a page reload during build

I have a very weird problem today and I hope one of you might be more experienced than I am in this regard and is able to help.

I started a Hudson build manually this morning, while this build was running I refreshed the page. In retrospect this might not have been the best idea, although I dont believe there is a connection between this and the error I am getting. But I could be wrong ofcourse. After the page finished refreshing, I was greeted by the following.

Now I always get this page when I open Hudson.

Any help will be greatly appreciated. If you need more information please ask. I wasnt sure what else to provide. To me it looks like a corrupted xml somwhere but I'm not sure where or what could have caused it.

Thanks for your help in advance.

Edit: (If you prefere text)

org.jvnet.hudson.reactor.ReactorException: com.google.common.util.concurrent.UncheckedExecutionException: com.thoughtworks.xstream.io.StreamException:  : only whitespace content allowed before start tag and not \u0 (position: START_DOCUMENT seen \u0... @1:1) 
at org.jvnet.hudson.reactor.Reactor.execute(Reactor.java:246)
at hudson.model.Hudson.executeReactor(Hudson.java:719)
at hudson.model.Hudson.<init>(Hudson.java:616)
at org.eclipse.hudson.init.InitialRunnable.run(InitialRunnable.java:51)
at java.lang.Thread.run(Unknown Source)
Caused by: com.google.common.util.concurrent.UncheckedExecutionException: com.thoughtworks.xstream.io.StreamException:  : only whitespace content allowed before start tag and not \u0 (position: START_DOCUMENT seen \u0... @1:1) 
at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2263)
at com.google.common.cache.LocalCache.get(LocalCache.java:4000)
at com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:4004)
at com.google.common.cache.LocalCache$LocalLoadingCache.get(LocalCache.java:4874)
at hudson.model.TopLevelItemsCache.get(TopLevelItemsCache.java:96)
at hudson.model.LazyTopLevelItem.item(LazyTopLevelItem.java:144)
at hudson.model.LazyTopLevelItem.hasPermission(LazyTopLevelItem.java:271)
at hudson.model.Hudson.getItems(Hudson.java:1303)
at hudson.model.Hudson.getItems(Hudson.java:223)
at hudson.model.Hudson.getAllItems(Hudson.java:1367)
at hudson.model.Hudson$12.run(Hudson.java:2481)
at org.jvnet.hudson.reactor.TaskGraphBuilder$TaskImpl.run(TaskGraphBuilder.java:146)
at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:259)
at hudson.model.Hudson$4.runTask(Hudson.java:699)
at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:187)
at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:94)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
... 1 more
Caused by: com.thoughtworks.xstream.io.StreamException:  : only whitespace content allowed before start tag and not \u0 (position: START_DOCUMENT seen \u0... @1:1) 
at com.thoughtworks.xstream.io.xml.XppReader.pullNextEvent(XppReader.java:124)
at com.thoughtworks.xstream.io.xml.AbstractPullReader.readRealEvent(AbstractPullReader.java:148)
at com.thoughtworks.xstream.io.xml.AbstractPullReader.readEvent(AbstractPullReader.java:141)
at com.thoughtworks.xstream.io.xml.AbstractPullReader.move(AbstractPullReader.java:118)
at com.thoughtworks.xstream.io.xml.AbstractPullReader.moveDown(AbstractPullReader.java:103)
at com.thoughtworks.xstream.io.xml.XppReader.<init>(XppReader.java:83)
at com.thoughtworks.xstream.io.xml.XppReader.<init>(XppReader.java:70)
at hudson.model.RunMap.loadFromRunMapXml(RunMap.java:690)
at hudson.model.RunMap.load(RunMap.java:591)
at hudson.model.AbstractProject.onLoad(AbstractProject.java:330)
at hudson.model.BaseBuildableProject.onLoad(BaseBuildableProject.java:94)
at hudson.model.TopLevelItemsCache$1.load(TopLevelItemsCache.java:82)
at hudson.model.TopLevelItemsCache$1.load(TopLevelItemsCache.java:75)
at com.google.common.cache.LocalCache$LoadingValueReference.loadFuture(LocalCache.java:3599)
at com.google.common.cache.LocalCache$Segment.loadSync(LocalCache.java:2379)
at com.google.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2342)
at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2257)
... 18 more
Caused by: org.xmlpull.v1.XmlPullParserException: only whitespace content allowed before start tag and not \u0 (position: START_DOCUMENT seen \u0... @1:1) 
at org.xmlpull.mxp1.MXParser.parseProlog(MXParser.java:1519)
at org.xmlpull.mxp1.MXParser.nextImpl(MXParser.java:1395)
at org.xmlpull.mxp1.MXParser.next(MXParser.java:1093)
at com.thoughtworks.xstream.io.xml.XppReader.pullNextEvent(XppReader.java:109)
... 34 more

Solution

We finally have been able to fix the problem. We found someone with a similar issue after a lot of googling. The answer is found here

I hope this helps someone in the future.